Method of verifying integrity of a post-process removal of support material

ABSTRACT

A method of manufacturing a three dimensional article includes forming the three-dimensional article with three-dimensional printing, processing the three-dimensional article to remove support material ink, illuminating the three-dimensional article with electromagnetic radiation, inspecting the three dimensional article for photoluminescence that is responsive to the illumination, and verifying whether the support material has been sufficiently removed based upon the inspection. The support material ink includes a phosphor component that phosphorescently emits light in response to the illumination.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims priority to U.S.Provisional Application Ser. No. 62/688,791, Entitled “METHOD OFVERIFYING INTEGRITY OF A POST-PROCESS REMOVAL OF SUPPORT MATERIAL” byMark Raymond Parker et al., filed on Jun. 22, 2018, incorporated hereinby reference under the benefit of U.S.C. 119(e). This non-provisionalpatent application also claims priority to U.S. Provisional ApplicationSer. No. 62/688,802, Entitled “METHOD FOR VERIFYING INTEGRITY OF A POSTPROCESS” by Mark Raymond Parker et al., filed on Jun. 22, 2018,incorporated herein by reference under the benefit of U.S.C. 119(e).

FIELD OF THE INVENTION

The present disclosure concerns materials for forming solidthree-dimensional articles from the selective deposition of materialsfrom an inkjet printhead. More particularly, the present disclosure amethod for verifying the integrity of a post-process removal of supportmaterial from build material.

BACKGROUND

Three-dimensional printing systems are in rapidly increasing use forpurposes such as prototyping and manufacturing. One type of 3D printerutilizes an inkjet printhead to selectively deposit a material tomanufacture a three-dimensional article. Typically, such a printerutilizes a “build material” to form the three-dimensional article and asupport material for supporting what would otherwise be unsupportedregions of build material during manufacture. The build material islater removed in a post-process. One challenge is verifying an integrityof the removal process.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic block diagram of an embodiment of athree-dimensional printing system.

FIG. 2 is a schematic diagram of a printhead assembly utilized in theprinting system of FIG. 1.

FIG. 3 is an illustration of an embodiment of a three-dimensionalarticle.

FIG. 3A is a cross-section taken through AA of FIG. 3.

FIG. 4 is a flowchart depicting an embodiment of a manufacturing processfor a three-dimensional article and determining whether a post-processparameter is in specification.

FIG. 5 is a flowchart depicting an embodiment of a manufacturing processfor forming a three-dimensional article while verifying completeness ofa post process removal of support material.

FIG. 6 is an illustration of an embodiment of a test coupon forevaluating a post-process.

FIG. 7 is a flowchart depicting an embodiment of a process forevaluating a post process removal parameter based upon a test coupon.

FIG. 8 is an embodiment of a portion of a three-dimensional articlehaving encapsulated indicia.

FIG. 8A is a cross-section taken through AA of FIG. 8.

FIG. 9 is a flowchart depicting an embodiment of a process for formingand reading the indicia of FIG. 8.

FIG. 10 is a flowchart depicting an embodiment of a process foroperating and maintaining a three-dimensional printer that utilizesheated phase change inks.

SUMMARY

In a first aspect of the disclosure, a method of manufacturing a threedimensional article includes forming the three-dimensional article withthree-dimensional printing, processing the three-dimensional article toremove support material ink, illuminating the three-dimensional articlewith electromagnetic radiation, inspecting the three dimensional articlefor photoluminescence that is responsive to the illumination, andverifying whether the support material has been sufficiently removedbased upon the inspection. Forming the three-dimensional article caninclude supplying inks to a printhead assembly, printing a layer of thethree-dimensional article using the printhead assembly, and repeatingsupplying and printing until the three-dimensional article is fullyformed. The inks include a build material ink and a support materialink. The support material ink is a phase change ink including a phosphorcomponent. During printing, the support material is printed to providesupport to otherwise unsupported portions of the build material.

In one implementation the support material ink can include 50 to 80weight percent phase change wax component, 5 to 50 tackifier component,and 0.01 to 5 percent phosphor component, based upon the total weight ofthe support material. The phase change component can include one or moreof a hydrocarbon wax, a fatty alcohol wax, a fatty acid wax, a fattyacid ester wax, an aldehyde wax, an amide wax, and a ketone wax. Thephase change component can be present in an amount of 60 to 70 weightpercent based on the total weight of the support material. The tackifiercomponent can include one or more of a rosin ester and a rosin alcohol.The tackifier component can be present in an amount of 25 to 45 weightpercent based on the total weight of the support material.

In another implementation the phosphor component can have a peakphotoluminescence emission wavelength in a range of 450 to 750nanometers and a photoluminescence quantum yield of 0.10 to 1. Thephosphor component can be responsive to an illumination wavelength of100 to 400 nanometers. The phosphor component can have a peakphotoluminescence emission wavelength of 500 to 700 nanometers and havea photoluminescence quantum yield of 0.10 to 1.

In yet another implementation the inspection occurs concurrently withthe illumination. The illumination can be with ultraviolet (UV) lightand the photoluminescence can be visible light. The illumination can bewith visible blue and/or violet light and the photoluminescence can bevisible light having a longer wavelength than the illumination light.

In a further implementation the three-dimensional article includes abuild material wall that encloses a hollow cavity and includes supportmaterial within the hollow cavity before post-processing. Illuminationis performed to the build material wall and to the cavity. Any remainingsupport material responds to the illumination and emits light thatpasses through the build material wall to be visible during inspection.

In a yet further implementation the processing to remove the supportmaterial ink is repeated if the verification determines that the supportmaterial has not be sufficiently removed.

In another implementation, the three-dimensional article is amanufacturing test coupon and wherein verifying includes determiningwhether the processing is within a specification based on theinspection. The test coupon can include a substrate formed from buildmaterial having an outside surface defining a plurality of openings thatindividually vary in size according to a dimension of the opening and aplurality of sacrificial portions that at least partially close theplurality of openings. The sacrificial portions are formed from asupport material that includes a phosphor component. The determinationcan be based upon a dimensional range of the openings that are clearedof the sacrificial portions. The opening dimension can be a hydraulicdiameter. The opening dimension can be a depth that the opening extendsinto the substrate. The openings can extend through the substrate. Thesubstrate can vary in thickness to provide a variable axial length ofthe openings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments described herein can be understood more readily by referenceto the following detailed description and examples. Elements, apparatusand methods described herein, however, are not limited to the specificembodiments presented in the detailed description and examples. Itshould be recognized that these embodiments are merely illustrative ofthe principles of the present invention. Numerous modifications andadaptations will be readily apparent to those of skill in the artwithout departing from the spirit and scope of the invention.

In addition, all ranges disclosed herein are to be understood toencompass any and all subranges subsumed therein. For example, a statedrange of “1.0 to 10.0” should be considered to include any and allsubranges beginning with a minimum value of 1.0 or more and ending witha maximum value of 10.0 or less, e.g., 1.0 to 5.3, or 4.7 to 10.0, or3.6 to 7.9. Similarly, a stated range of “1 to 100” should be consideredto include any and all subranges beginning with a minimum value of 1 ormore and ending with a maximum value of 100 or less, e.g., 1 to 49, or33 to 70, or 17 to 100.

All ranges disclosed herein are also to be considered to include the endpoints of the range, unless expressly stated otherwise. For example, arange of “between 5 and 10” should generally be considered to includethe end points 5 and 10.

Further, when the phrase “up to” is used in connection with an amount orquantity, it is to be understood that the amount is at least adetectable amount or quantity. For example, a material present in anamount “up to” a specified amount can be present from a detectableamount and up to and including the specified amount.

The terms “three-dimensional printing system,” “three-dimensionalprinter,” “printing,” and the like generally describe various solidfreeform fabrication techniques for making three-dimensional articles orobjects by selective deposition, jetting, fused deposition modeling,multijet modeling, and other techniques now known in the art or that maybe known in the future that use a build material or ink to fabricatethree-dimensional objects, parts, or articles.

FIG. 1 is a schematic block diagram of an embodiment of a printingsystem 2. In describing the printing system 2, mutually orthogonal axesX, Y, and Z are utilized. The axes X and Y will be referred to “lateral”or “horizontal” axes and Z will be described as a “vertical” axis.However, it is to be understood that Z is not necessarily perfectlyaligned with a gravitational reference. Also X will refer to a “scan”axis and Y will refer to a “transverse” axis. The direction+Z isreferred to as a generally “upward” direction and −Z is a generally“downward” direction.

Printing system 2 includes an elevator mechanism 6 for supporting,aligning, and vertically positioning a build plate 4. The build plate 4is typically formed from a rigid material such as aluminum or steel andincludes an upper surface upon which a three-dimensional (3D) article 7is to be formed. The rigidity is important so that accurate positionaland dimensional tolerances can be achieved. The elevator mechanism 6 isconfigured to controllably position the build plate 4 along the verticalaxis Z.

Printing system 2 includes a printhead assembly 8 that is supported andlaterally translated by a movement mechanism 10. Movement mechanism 10is configured to translate the printhead assembly 8 along scan axis λ asprinthead assembly 8 selectively deposits drops of ink onto the buildplate 6 to form layers of a three-dimensional (3D) article ofmanufacture. In alternative embodiments, the build plate is mounted to amovement mechanism that laterally translates the build plate, and theprinthead assembly is mounted to an elevator mechanism to verticallyposition the printhead assembly relative to the build plate. Furtherembodiments of the present invention include alternative mechanisms formoving the printhead assembly relative to the build plate in the X, Y,and Z axes.

Printhead assembly 8 receives ink(s) from an ink supply 12 via an inkpath(s) 14. In an exemplary embodiment the ink path 14 is a heated tubethat transports a phase change ink from ink supply 12 to the printheadassembly 8. Controller 16 is configured to operate the printing system 2for printing a three-dimensional (3D) article of manufacture 7.

The method of printing to form the three-dimensional article 7 is alayer-by-layer process. The ink supply 12 includes at least twodifferent inks including a build material ink 9 and a sacrificialsupport material ink 11. The printing method includes supplying the inksto the printhead assembly 8 including the build material ink 9 and thesupport material ink 11, printing a layer of the three-dimensionalarticle 7 using the printhead assembly 8, and repeating the supplyingand printing until the three-dimensional article 7 is fully formed.Individual layers are nearly planar over axes X and Y. For theillustrated three-dimensional article 7, there is a portion 13 of buildmaterial 9 that would be unsupported without the support material 11.After the manufacturing process it is desired that the support material11 be removed. Thus a post-process is performed to remove the supportmaterial 11. Material 11 is called “sacrificial support material” 11because it is generally a temporary or sacrificial material later to beremoved from the three-dimensional article 7.

FIG. 2 schematically depicts an exemplary printhead assembly 8 along thescan axis X. Arranged along X, the printhead assembly 8 includes two UVlamps 20, two fans 22, a planarizer roller 24, and a printhead 26. Theprinthead 26 has a lower face 28. The planarizer roller 24 is configuredto impact and planarize material that extends above a planarizing plane30. A vertical distance HT extends between the lower face 28 and theplanarizing plane 30.

The printhead(s) 26 can include different groups of nozzles to printdifferent inks. If some of these inks are UV curable (curable withultraviolet light) then the UV lamp 20 can be operated to cure the inks.In some embodiments the printing system 2 will not utilize UV curableinks and then the UV lamps 20 are not required.

In one embodiment the printhead assembly 8 includes one printhead 26that is configured to eject two different inks including a buildmaterial 9 and a support material 11. In another embodiment theprinthead assembly 8 includes two different printheads 26—one to eject abuild material 9 and one to eject a support material 11. In yet anotherembodiment, the printing system 2 can include two different printheadassemblies 8—one for ejecting a build material 9 and another forejecting a support material 11. In further embodiments, the printingsystem 2 can include additional printheads 26 for ejecting multiplebuild materials 9 that can vary in terms of color, elastic modulus,fillers, and other properties and aspects.

I. Build Materials

In one aspect, build materials for use with a 3D printing system aredescribed herein. A build material described herein can comprise one ormore components that provide mechanical structure to a printed 3Darticle formed from the build material, as well as a phosphor component.As understood by one of ordinary skill in the art, components thatprovide mechanical structure can include a variety of materials orchemical species. For instance, in some cases, such components are“phase change” components that undergo a rapid phase change (e.g., fluidto solid) upon deposition onto a substrate, thereby forming a solidvoxel of a layer of a printed article. In other instances, structuralcomponents of a build material are curable. Curable components, asunderstood by one of ordinary skill in the art, can be deposited in ashape-unstable or quasi-unstable state and then cured (e.g.,polymerized) to form a shape-stable voxel of a layer of a printed 3Darticle. Such “structural” components of a build material can compriseor form the majority of the build material described herein. Moreover,such “structural” components generally exclude additives such ascolorants, stabilizers, and inhibitors.

In general, the types of structural components of a build materialdescribed herein are not particularly limited. However, some preferredcompositions are particularly described further hereinbelow.

In some preferred embodiments, a build material described hereincomprises at least 70 wt. % phase change wax component, optionally up to30 wt. % additive component, and 0.001-5 wt. % phosphor component, basedon the total weight of the build material. In some such cases, the phasechange wax component is present in the build material in an amount of atleast 85 wt. %, the additive component is present in the build materialin an amount of 2-10 wt. %, and the phosphor component is present in thebuild material in an amount of 0.001-0.5 wt. %, 0.005-0.5 wt. %, or0.01-0.5 wt. %, based on the total weight of the build material.

In other embodiments, a build material described herein comprises 10-60wt. % oligomeric curable material, up to 80 wt. % monomeric curablematerial, and 0.001-0.5 wt. %, 0.005-0.5 wt. %, or 0.01-0.5 wt. %phosphor component, based on the total weight of the build material. Insome such instances, the oligomeric curable material is present in thebuild material in an amount of 10-30 wt. %, the monomeric curablematerial is present in the build material in an amount of 40-70 wt. %,and the phosphor component is present in the build material in an amountof 0.001-0.5 wt. %, based on the total weight of the build material.

A build material described herein can also include one or more othercomponents, in addition to those described above. For example, in somecases, a build material described herein comprises at least onecolorant, at least one photoinitiator, at least one inhibitor, at leastone stabilizing agent, or a combination of two or more of the foregoingclasses of additional components.

Turning now to specific components of build materials, a build materialdescribed herein, in some embodiments, comprises a phase change waxcomponent. Any phase change wax component not inconsistent with theobjectives of the present disclosure may be used. Moreover, in somecases, the phase change wax component comprises a plurality or blend ofdiffering waxes. In some instances, the phase change wax componentcomprises a hydrocarbon wax, a fatty alcohol wax, a fatty acid wax, afatty acid ester wax, an aldehyde wax, an amide wax, a ketone wax, or amixture or combination thereof.

A hydrocarbon wax, in some embodiments, comprises a paraffin wax. Such aparaffin wax can comprise one or more linear (or n-) alkanes, branched(or iso-) alkanes, naphthenes, or alkyl- or naphthene-substitutedaromatic hydrocarbons. For example, in some cases, a paraffin waxcomprises one or more C9-C60 alkanes. As understood by one of ordinaryskill in the art, a “Cn” alkane (or other species) is an alkane (orother species) having “n” carbon atoms. In some instances, a hydrocarbonwax comprises a C9-C40 alkane, a C9-C30 alkane, a C16-C60 alkane, aC16-C40 alkane, a C16-C30 alkane, a C20-C60 alkane, a C20-C50 alkane, ora C20-C40 alkane. Moreover, in some embodiments, a hydrocarbon waxcomponent comprises a plurality of differing species, including acombination of differing species (e.g., linear alkanes, branchedalkanes, and/or naphthenic hydrocarbons) mentioned above.

A fatty alcohol wax, in some instances, comprises a fatty alcohol. Anyfatty alcohol not inconsistent with the objectives of the presentdisclosure may be used. In some cases, a fatty alcohol has the generalformula C_(n)H_(2n+1)OH, wherein n is an integer from 6 to 36 or from 8to 28. In some embodiments, for example, a fatty alcohol comprisesdecanol (C₁₀H₂₁OH), dodecanol (C₁₂H₂₅OH), tetradecanol (C₁₄H₂₉OH),hexadecanol (C₁₆H₃₃OH), octadecanol (C₁₈H₃₇OH), eicosanol (C₂₀H₄₁OH) ordocosanol (C₂₂H₄₅OH), or a mixture or combination thereof. Further, afatty alcohol described herein, in some cases, can be a primary alcoholsuch as stearyl alcohol or behenyl alcohol. Other fatty alcohols mayalso be used.

Further, an alcohol wax described herein can also comprise a syntheticlong chain alcohol or a hydroxyl-terminated hydrophobic polymer, such asa hydroxyl-terminated polyethylene. For example, in some cases, analcohol wax described herein comprises UNILIN 350, UNILIN 425, UNILIN550, and/or UNILIN 700.

Moreover, an alcohol wax described herein, in some cases, include analkoxylated (e.g., ethoxylated) alcohol wax, such as an ethoxylatedbehenyl alcohol (e.g., NOVEL 22-25 Ethoxylate).

A fatty acid wax, in some embodiments, comprises a fatty carboxylic acidor fatty acid. Any fatty acid not inconsistent with the objectives ofthe present disclosure may be used. In some cases, a fatty acid has thegeneral formula C_(n)H_(2n+1)COOH, wherein n is an integer from 6 to 36or from 8 to 28 or from 24 to 49. In some embodiments, for example, afatty acid comprises lauric acid (C₁₁H₂₃COOH), myristic acid(C₁₃H₂₇COOH), palmitic acid (C₁₅H₃₁COOH), stearic acid (C₁₇H₃₅COOH),behenic acid (C₂₁H₄₃COOH), or a mixture or combination thereof. A fattyacid wax described herein, in some cases, is a synthetic acid wax suchas UNICID 350 or UNICID 550 (commercially available from Baker Hughes).Other fatty acids may also be used.

Further, an acid wax described herein can also comprise a synthetic longchain carboxylic acid or a carboxyl-terminated hydrophobic polymer, suchas a carboxyl-terminated polyethylene.

A fatty acid ester wax, in some embodiments, comprises an alkyl alkylester, an alkyl aryl ester, an alkyl arylalkyl ester, an alkyl alkylarylester, or a combination or mixture of two or more of the foregoing. Forexample, in some cases, a fatty acid ester wax of a build materialdescribed herein comprises an ester having the general formulaR—(C═O)—OR′, wherein R and R′ are each independently an alkyl groupdescribed hereinabove for a fatty acid wax or as described hereinbelowfor ketone waxes, such as an alkyl group having between 1 and 36 carbonatoms, provided that at least one of R and R′ is an alkyl group havingat least 4 carbon atoms. In some cases, such an alkyl group is linear.An alkyl group of a fatty acid ester wax described herein can also bebranched, cyclic, saturated, unsaturated, substituted, or unsubstituted.An ester wax can also have the general formula R—(C═O)—OAr, RO—(C═O)—Ar,Ar—(C═O)—OAr′, ArO—(C═O)—RAr′, Ar—(C═O)—ORAr′, ArO—(C═O)—Ar′R,Ar—(C═O)—OAr′R, ArR—(C═O)—OAr′R, ArR—(C═O)—OR′Ar′, or RAr—(C═O)—OR′Ar′,wherein Ar and Ar′ are each independently an aryl group describedhereinbelow for ketone waxes and R and R′ are each independently analkyl group described above. For example, in some embodiments, Ar andAr′ are each an aryl group having 6 to 36 carbon atoms. One non-limitingexample of an ester wax suitable for use in some embodiments describedherein is methyl behenate (CH₃O—(C═O)—CH₂(CH₂)₂₀CH₃). Other ester waxesmay also be used.

Moreover, when an ester wax described herein comprises a substitutedalkyl, aryl, alkylaryl, or arylalkyl group, one or more substituents ofthe substituted group, in some cases, can comprise a substituent groupdescribed hereinbelow for substituted ketone waxes.

An aldehyde wax described herein, in some embodiments, comprises analkyl aldehyde, an aryl aldehyde, an arylalkyl aldehyde, an alkylarylaldehyde, or a combination or mixture of two or more of the foregoing.For example, in some cases, an aldehyde wax of a build materialdescribed herein comprises an aldehyde having the general formulaR—(O═O)—H, wherein R is an alkyl group described hereinabove for a fattyacid wax or as described hereinbelow for ketone waxes, such as an alkylgroup having between 4 and 36 carbon atoms or between 9 and 36 carbonatoms. In some cases, such an alkyl group is linear. An alkyl group ofan aldehyde wax described herein can also be branched, cyclic,saturated, unsaturated, substituted, or unsubstituted. An ester wax canalso have the general formula R—(C═O)—H, Ar—(C═O)—H, ArO—(C═O)—H,ArR—(C═O)—H, or RAr—(C═O)—H, wherein Ar is an aryl group describedhereinbelow for ketone waxes and R is an alkyl group described above.For example, in some embodiments, Ar is an aryl group having 6 to 36carbon atoms.

Moreover, when an aldehyde wax described herein comprises a substitutedalkyl, aryl, alkylaryl, or arylalkyl group, one or more substituents ofthe substituted group, in some cases, can comprise a substituent groupdescribed hereinbelow for substituted ketone waxes.

An amide wax, in some embodiments, comprises an alkyl alkyl amide orbis(amide), an alkyl aryl amide or bis(amide), an aryl aryl amide orbis(amide), an aryl arylalkyl amide or bis(amide), an aryl alkylarylamide or bis(amide), an arylalkyl arylalkyl amide or bis(amide), anarylalkyl alkylaryl amide or bis(amide), an alkylaryl alkylaryl amide orbis(amide), or a combination or mixture of two or more of the foregoing.For example, in some cases, an amide wax described herein comprisesethylene bis(stearamide) (EBS). In other cases, an amide has the generalformula R—(C═O)—NHR′, wherein R and R′ are each independently an alkylgroup described hereinabove, such as an alkyl group having between 1 and36 carbon atoms, provided that at least one of R and R′ is an alkylgroup having at least 4 carbon atoms. In some cases, such an alkyl groupis linear. An alkyl group of an amide wax described herein can also bebranched, cyclic, saturated, unsaturated, substituted, or unsubstituted.An amide wax can also have the general formula R—(C═O)—NR″Ar,RNR″—(C═O)—Ar, Ar—(C═O)—NR″Ar, ArNR“—(C═O)—RAr, Ar—(C═O)—NR″RAr′,ArNR”—(C═O)—ArR, Ar—(C═O)—NR″ArR, ArR—(C═O)—NR″ArR, ArR—(C═O)—NR″R′Ar′,or RAr—(C═O)—NR″R′Ar′, wherein Ar and Ar′ are each independently an arylgroup described above, R and R′ are each independently an alkyl groupdescribed above, and R″ is hydrogen or an alkyl group described above.For example, in some embodiments, Ar and Ar′ are each an aryl grouphaving 6 to 36 carbon atoms. One non-limiting example of an amide waxsuitable for use in some embodiments described herein is stearylstearamide (CH₃(CH₂)₁₇—(C═O)—NH(CH₂)₁₇CH₃). Other amide waxes may alsobe used.

A ketone wax, in some cases, comprises an alkyl alkyl ketone, an alkylaryl ketone, an aryl aryl ketone, an aryl arylalkyl ketone, an arylalkylaryl ketone, an arylalkyl arylalkyl ketone, an arylalkyl alkylarylketone, an alkylaryl alkylaryl ketone, or a combination or mixture oftwo or more of the foregoing. For example, in some embodiments, a ketonewax described herein comprises an alkyl alkyl ketone having the generalformula R—(C═O)—R′, wherein R and R′ are each independently an alkylgroup having between 1 and 36 carbon atoms, provided that at least oneof R and R′ is an alkyl group having at least 4 carbon atoms. In somecases, such an alkyl group is linear. An alkyl group of a ketone waxdescribed herein can also be branched, cyclic, saturated, unsaturated,substituted, or unsubstituted. Non-limiting examples of alkyl alkylketones suitable for use in some embodiments of build materialsdescribed herein include n-octyl-n-propyl ketone; n-octyl-n-butylketone, n-decyl-n-ethyl ketone, n-undecyl-n-propyl ketone,n-dodecyl-n-ethyl ketone, di-n-hexylketone, di-n-heptylketone,di-n-octyl ketone, di-n-nonyl ketone, di-n-decyl ketone, di-n-undecylketone, di-n-tridecyl ketone, di-n-heptadecyl ketone, di-n-octadecylketone, and mixtures or combinations thereof. Other alkyl alkyl ketonesmay also be used.

Further, a ketone wax of described herein can also comprise an alkylaryl ketone having the general formula R—(C═O)—Ar, wherein R is an alkylgroup as described above for an alkyl alkyl ketone, and Ar is an arylgroup having 6 to 36 carbon atoms. The aryl group, in some cases,comprises a substituted or unsubstituted phenyl, naphthyl, or anthrylgroup. Non-limiting examples of alkyl aryl ketones suitable for use insome embodiments of build materials described herein include n-octylphenyl ketone, n-undecyl phenyl ketone, n-pentadecyl phenyl ketone,n-octadecyl phenyl ketone, and mixtures or combinations thereof. Otheralkyl aryl ketones may also be used.

In addition, in some embodiments, a ketone wax escribed herein comprisesan aryl aryl ketone having the general formula Ar—(C═O)—Ar, wherein Arand Ar′ are each independently an aryl group described above for alkylaryl ketones. Non-limiting examples of aryl aryl ketones suitable foruse in some embodiments of build materials described herein includediphenyl acetone, 2-naphthyl phenyl ketone, and mixtures or combinationsthereof. Other aryl aryl ketones may also be used.

Moreover, a ketone wax described herein can also comprise an arylarylalkyl ketone or an aryl alkylaryl ketone having the general formulaAr—(C═O)—Ar′R or Ar—(C═O)—RAr′, wherein R is an alkyl group describedhereinabove for an alkyl alkyl ketone, and Ar and Ar′ are eachindependently an aryl group described hereinabove for an aryl arylketone. One non-limiting example of an aryl alkylaryl ketone suitablefor use in some embodiments of build materials described herein isbenzyl phenyl ketone. Other aryl arylalkyl ketones or aryl alkylarylketones may also be used.

In addition, in some embodiments, a ketone wax described hereincomprises an arylalkyl arylalkyl ketone, an arylalkyl alkylaryl ketone,or an alkylaryl alkylaryl ketone having the general formulaRAr—(C═O)—ArR, RAr—(C═O)—R′Ar, or ArR—(C═O)—R′Ar′, wherein Ar and Ar′are each independently an aryl group described above and R and R′ areeach independently an alkyl group described above. One non-limitingexample of such a ketone is di-n-benzyl ketone. Other such ketones mayalso be used.

Moreover, when a ketone wax described herein comprises a substitutedalkyl, aryl, alkylaryl, or arylalkyl group, one or more substituents ofthe substituted group, in some cases, can comprise a hydroxy group,amine group, imine group, ammonium group, pyridine group, pyridiniumgroup, ether group, ester group, amide group, carbonyl group,thiocarbonyl group, sulfate group, sulfonate group, sulfide group,sulfoxide group, phosphine group, phosphonium group, phosphate group,mercapto group, nitroso group, sulfone group, acyl group, acid anhydridegroup, or azide group.

Additional examples of ketone waxes suitable for use in some embodimentsof build materials described herein include stearones such as T-1 (KaoCorporation); KLB-766 (C21-(C═O)—C21 ketone) (Kao Corporation); andKLB-770 (C17-(C═O)—C17 ketone) (Kao Corporation), and/or laurones suchas LAURONE (Kanto Kagaku Co. Ltd.).

Further, a phase change wax component of a build material describedherein can be present in the build material in any amount notinconsistent with the objectives of the present disclosure. In somecases, for instance, the phase change wax component is present in anamount of at least 70 wt. % or at least 85 wt. %, based on the totalweight of the build material. In some embodiments, the phase change waxcomponent is present in an amount of 70-99 wt. %, 70-95 wt. %, 70-90 wt.%, 70-85 wt. %, 75-99 wt. %, 75-95 wt. %, 75-90 wt. %, 75-85 wt. %,80-99 wt. %, 80-95 wt. %, 85-99 wt. %, 85-95 wt. %, or 85-90 wt. %,based on the total weight of the build material.

Turning now to other specific components of build materials describedherein, build materials described herein may further comprise one ormore oligomeric curable materials and/or one or more monomeric curablematerials. A curable material, for reference purposes herein, comprisesa chemical species that includes one or more curable or polymerizablemoieties. A “polymerizable moiety,” for reference purposes herein,comprises a moiety that can be polymerized or cured to provide a printed3D article or object. Such polymerizing or curing can be carried out inany manner not inconsistent with the objectives of the presentdisclosure. In some embodiments, for example, polymerizing or curingcomprises irradiating a polymerizable or curable material withelectromagnetic radiation having sufficient energy to initiate apolymerization or cross-linking reaction. For instance, in some cases,ultraviolet (UV) radiation can be used. Thus, in some instances, apolymerizable moiety comprises a photo-polymerizable or photo-curablemoiety, such as a UV-polymerizable moiety. In some embodiments, acurable material described herein is photo-polymerizable orphoto-curable at wavelengths ranging from about 300 nm to about 400 nmor from about 320 nm to about 380 nm. Alternatively, in other instances,a curable material is photo-polymerizable at visible wavelengths of theelectromagnetic spectrum.

Moreover, a polymerization reaction, in some cases, comprises a freeradical polymerization reaction, such as that between points ofunsaturation, including points of ethyleneic unsaturation. Otherpolymerization reactions may also be used. As understood by one ofordinary skill in the art, a polymerization reaction used to polymerizeor cure a curable material described herein can comprise a reaction of aplurality of “monomers” or chemical species having one or morefunctional groups or moieties that can react with one another to formone or more covalent bonds.

One non-limiting example of a polymerizable moiety of a curable materialdescribed herein is an ethyleneically unsaturated moiety, such as avinyl moiety, allyl moiety, or (meth)acrylate moiety, where the term“(meth)acrylate” includes acrylate or methacrylate or a mixture orcombination thereof.

“Oligomeric” species, which are contained in the oligomeric curablematerial described herein, are themselves polymers or oligomers and havea relatively high molecular weight or a relatively high viscosity. Thesespecies are also capable of undergoing additional polymerization, suchas through one or more points of unsaturation described herein. Apopulation of oligomeric species in the oligomeric curable materialdescribed herein can have varying molecular structures and/or formulasthroughout the population (such as may be exhibited, for example, by aspecified mass of a urethane acrylate having a non-unity molecularweight distribution, or by a specified mass of an ethoxylatedpolyethylene glycol having a distribution of ethylene glycol unitsand/or a distribution of ethoxy units within the population). The weightaverage molecular weight of an oligomeric curable material describedherein can generally be in the range from about 400 to 10,000, fromabout 600 to 10,000, or from about 500 to 7,000.

In contrast to an “oligomeric” species, “monomeric” species, which arecontained in the additional monomeric material described herein, are notthemselves a polymer or oligomer, and have a relatively low molecularweight or a relatively low viscosity. “Monomeric” species contained inthe additional monomeric curable material can have a consistent orwell-defined molecular structure and/or formula throughout thepopulation (such as may be exhibited, for instance, by a specified massof ethoxylated (4) bisphenol A diacrylate or a specific mass of theabove-described curable monomer). Additionally, in some embodiments, anadditional monomeric curable material as described herein has aviscosity of 500 centipoise (cP) or less at 25° C., when measuredaccording to ASTM D2983, while an “oligomeric” curable material has aviscosity of 1000 cP or more at 25° C., when measured according to ASTMD2983.

One non-limiting example of a polymerizable moiety of the oligomericcurable material or the additional monomeric curable material describedherein is an ethylenically unsaturated moiety, such as a vinyl moiety,allyl moiety, or (meth)acrylate moiety, where the term “(meth)acrylate”includes acrylate or methacrylate or a mixture or combination thereof.

Additionally, the oligomeric curable material and the additionalmonomeric curable material described herein can comprise amonofunctional, difunctional, trifunctional, tetrafunctional,pentafunctional, or higher functional curable species. A“monofunctional” curable species, for reference purposes herein,comprises a chemical species that includes one curable or polymerizablemoiety. Similarly, a “difunctional” curable species comprises a chemicalspecies that includes two curable or polymerizable moieties; a“trifunctional” curable species comprises a chemical species thatincludes three curable or polymerizable moieties; a “tetrafunctional”curable species comprises a chemical species that includes four curableor polymerizable moieties; and a “pentafunctional” curable speciescomprises a chemical species that includes five curable or polymerizablemoieties. Thus, in some embodiments, a monofunctional curable materialof a build material described herein comprises a mono(meth)acrylate, adifunctional curable material of a build material described hereincomprises a di(meth)acrylate, a trifunctional curable material of abuild material described herein comprises a tri(meth)acrylate, atetrafunctional curable material of a build material described hereincomprises a tetra(meth)acrylate, and a pentafunctional curable materialof a build material described herein comprises a penta(meth)acrylate.Other monofunctional, difunctional, trifunctional, tetrafunctional, andpentafunctional curable materials may also be used.

Moreover, a monofunctional, difunctional, trifunctional,tetrafunctional, and pentafunctional curable material, in some cases,can comprise a relatively low molecular weight species, i.e., amonomeric species, or a relatively high molecular weight species, i.e.,an oligomeric species.

In general, any oligomeric curable material not inconsistent with theobjectives of the present disclosure may be used in a build materialdescribed herein. In some cases, for instance, an oligomeric curablematerial comprises a polyester (meth)acrylate oligomer, a urethane(meth)acrylate oligomer, or an epoxy(meth)acrylate oligomer. Further, insome embodiments, an oligomeric curable material described hereincomprises an aliphatic polyester urethane acrylate oligomer and/or anacrylate amine oligomeric resin, such as EBECRYL 7100. In some cases, anoligomeric curable material described herein comprises a polypropyleneglycol mono(meth)acrylate or polyethylene glycol mono(meth)acrylate. Insome embodiments, an oligomeric curable material comprises amonofunctional aliphatic urethane (meth)acrylate. Moreover, in somecases, an oligomeric curable material comprises a diacrylate and/ordimethacrylate ester of an aliphatic, cycloaliphatic or aromatic diol,including polyethylene glycol, ethoxylated or propoxylated neopentylglycol, ethoxylated or propoxylated bisphenol A, ethoxylated orpropoxylated bisphenol F, ethoxylated or propoxylated bisphenol S,ethoxylated or propoxylated 1,1,1-trimethylolpropanetri(meth)acrylate,or ethoxylated or propoxylated glycerol tri(meth)acrylate.

Some non-limiting examples of commercially available oligomeric curablematerials useful in some embodiments described herein include thefollowing: alkoxylated tetrahydrofurfuryl acrylate, commerciallyavailable from SARTOMER under the trade name SR 611; monofunctionalurethane acrylate, commercially available from RAHN USA under the tradename GENOMER 1122; an aliphatic urethane diacrylate, commerciallyavailable from ALLNEX under the trade name EBECRYL 8402; amultifunctional acrylate oligomer, commercially available from DYMAXCorporation under the trade name BR-952; aliphatic polyether urethaneacrylate, commercially available from DYMAX Corporation under the tradename BR-371S; and an aliphatic polyether urethane methacrylate,commercially available from DYMAX Corporation under the trade nameBR-541 MB. Other commercially available oligomeric curable materials mayalso be used.

Urethane (meth)acrylates suitable for use in build materials describedherein, in some cases, can be prepared in a known manner, typically byreacting a hydroxyl-terminated urethane with acrylic acid or methacrylicacid to give the corresponding urethane (meth)acrylate, or by reactingan isocyanate-terminated prepolymer with hydroxyalkyl acrylates ormethacrylates to give the urethane (meth)acrylate. Suitable processesare disclosed, inter alia, in EP-A 114 982 and EP-A 133 908. The weightaverage molecular weight of such (meth)acrylate oligomers, in somecases, can be from about 400 to 10,000 or from about 500 to 7,000.Urethane (meth)acrylates are also commercially available from SARTOMERunder the product names CN980, CN981, CN975 and CN2901, or from BOMARSpecialties Co. under the product name BR-741. In some embodimentsdescribed herein, a urethane (meth)acrylate oligomer has a viscosityranging from about 140,000 centipoise (cP) to about 160,000 cP at about50° C. or from about 125,000 cP to about 175,000 cP at about 50° C. whenmeasured in a manner consistent with ASTM D2983. In some cases, aurethane (meth)acrylate oligomer has a viscosity ranging from about100,000 cP to about 200,000 cP at about 50° C. or from about 10,000 cPto about 300,000 cP at about 50° C. when measured in a manner consistentwith ASTM D2983.

The oligomeric curable material can be present in a build materialdescribed herein in any amount not inconsistent with the objectives ofthe present disclosure. In some cases, the oligomeric curable material,in total, is present in the build material in an amount up to about 80wt. %, up to about 70 wt. %, up to about 60 wt. %, up to about 50 wt. %,up to about 40 wt. %, up to about 30 wt. %, or up to about 20 wt. %,based on the total weight of the build material. In some instances, abuild material described herein comprises about 10-80 wt. % of theoligomeric curable material, based on the total weight of the buildmaterial. In some embodiments, a build material comprises about 10-70wt. %, 10-60 wt. %, 10-50 wt. %, 10-40 wt. %, 10-30 wt. %, 10-20 wt. %,15-80 wt. %, 15-70 wt. %, 15-40 wt. %, 15-30 wt. %, 20-80 wt. %, 20-70wt. %, 20-60 wt. %, 20-50 wt. %, 20-40 wt. %, 30-80 wt. %, 30-70 wt. %,30-60 wt. %, 30-50 wt. %, 40-80 wt. %, 40-70 wt. %, or 40-60 wt. % ofthe oligomeric curable material, based on the total weight of the buildmaterial.

In addition, any monomeric curable materials not inconsistent with theobjectives of the present disclosure may be used as the monomericcurable material described herein. In some cases, the monomeric curablematerial of a build material described herein comprises one or morespecies of (meth)acrylates, such as one or more monofunctional,difunctional, trifunctional, tetrafunctional (meth)acrylates, and/orpentafunctional (meth)acrylates. In some embodiments, for instance, amonomeric curable material comprises methyl (meth)acrylate, ethyl(meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate,isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate,n-dodecyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2- or3-hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate,2-ethoxyethyl (meth)acrylate, 2- or 3-ethoxypropyl (meth)acrylate,tetrahydrofurfuryl methacrylate, isobornyl (meth)acrylate,2-(2-ethoxyethoxy)ethyl acrylate, cyclohexyl methacrylate,2-phenoxyethyl acrylate, glycidyl acrylate, isodecyl acrylate,2-phenoxyethyl (meth)acrylate, lauryl methacrylate, or a combinationthereof. In some embodiments, a monomeric curable material comprises oneor more of allyl acrylate, allyl methacrylate, triethylene glycoldi(meth)acrylate, tricyclodecane dimethanol diacrylate, and cyclohexanedimethanol diacrylate. Additionally, in some cases, a monomeric curablematerial comprises diacrylate and/or dimethacrylate esters of aliphatic,cycloaliphatic or aromatic diols, including 1,3- or 1,4-butanediol,neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol,tetraethylene glycol, tripropylene glycol,1,4-dihydroxymethylcyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane orbis(4-hydroxycyclohexyl)methane, hydroquinone, 4,4′-dihydroxybiphenyl,bisphenol A, bisphenol F, or bisphenol S. A monomeric curable materialdescribed herein may also comprise 1,1-trimethylolpropanetri(meth)acrylate, pentaerythritol monohydroxy tri(meth)acrylate,dipentaerythritol monohydroxy penta(meth)acrylate, and/orbis(trimethylolpropane) tetra(meth)acrylate. Further, in some cases, amonomeric curable material can comprise an ethoxylated or propoxylatedspecies, such as ethoxylated or propoxylated neopentyl glycol,ethoxylated or propoxylated bisphenol A, ethoxylated or propoxylatedbisphenol F, ethoxylated or propoxylated bisphenol S, ethoxylated orpropoxylated 1,1,1-trimethylolpropanetri(meth)acrylate, or ethoxylatedor propoxylated glycerol tri(meth)acrylate.

Additional non-limiting examples of commercially available monomericcurable materials useful as the monomeric curable material in someembodiments described herein include the following: isobornyl acrylate(IBOA), commercially available from SARTOMER under the trade name SR506; isobornyl methacrylate, commercially available from SARTOMER underthe trade name SR 423A; triethylene glycol diacrylate, commerciallyavailable from SARTOMER under the trade name SR 272; triethylene glycoldimethacrylate, commercially available from SARTOMER under the tradename SR 205; tricyclodecane dimethanol diacrylate, commerciallyavailable from SARTOMER under the trade name SR 833S; tris(2-hydroxyethyl)isocyanurate triacrylate, commercially available from SARTOMERunder the trade name SR 368; 2-phenoxyethyl acrylate, commerciallyavailable from SARTOMER under the trade name SR 339; ethyoxylated (3mole) bisphenol A diacrylate, commercially available from SARTOMER underthe trade name SR 349; a cyclic monofunctional acrylate, commerciallyavailable by RAHN USA Corp. under the trade name GENOMER 1120; anddipentaerythritol pentaacrylate, commercially available from SARTOMERunder the trade name SR 399 LV. Other commercially available monomericcurable materials may also be used.

The monomeric curable material can be present in a build materialdescribed herein in any amount not inconsistent with the objectives ofthe present disclosure. In some cases, the monomeric curable material,in total, is present in an amount up to about 80 wt. %, up to about 70wt. %, up to about 60 wt. %, or up to about 50 wt. %, based on the totalweight of the build material. In some cases, a build material describedherein comprises about 0-80 wt. % monomeric curable material, based onthe total weight of the build material. In some embodiments, a buildmaterial comprises about 30-80 wt. %, 30-70 wt. %, 30-60 wt. %, 30-50wt. %, 30-40 wt. %, 40-80 wt. %, 40-70 wt. %, 40-60 wt. %, 50-80 wt. %,or 50-70 wt. % monomeric curable material, based on the total weight ofthe build material.

Turning to another component of build materials described herein, buildmaterials described herein can further comprise at least onephotoinitiator. Any photoinitiator not inconsistent with the objectivesof the present disclosure may be used. In some cases, a photoinitiatorcomprises an alpha-cleavage type (unimolecular decomposition process)photoinitiator or a hydrogen abstraction photosensitizer-tertiary aminesynergist, operable to absorb light between about 250 nm and about 400nm or between about 300 nm and about 385 nm, to yield free radical(s).Examples of alpha cleavage photoinitiators are Irgacure 184 (CAS947-19-3), Irgacure 369 (CAS 119313-12-1), and Irgacure 819 (CAS162881-26-7). An example of a photosensitizer-amine combination isDarocur BP (CAS 119-61-9) with diethylaminoethylmethacrylate.

In addition, in some instances, photoinitiators comprise benzoins,including benzoin, benzoin ethers, such as benzoin methyl ether, benzoinethyl ether and benzoin isopropyl ether, benzoin phenyl ether andbenzoin acetate, acetophenones, including acetophenone,2,2-dimethoxyacetophenone and 1,1-dichloroacetophenone, benzil, benzilketals, such as benzil dimethyl ketal and benzil diethyl ketal,anthraquinones, including 2-methylanthraquinone, 2-ethylanthraquinone,2-tert-butylanthraquinone, 1-chloroanthraquinone and2-amylanthraquinone, triphenylphosphine, benzoylphosphine oxides, suchas 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO),benzophenones, such as benzophenone and4,4′-bis(N,N′-dimethylamino)benzophenone, thioxanthones and xanthones,acridine derivatives, phenazine derivatives, quinoxaline derivatives or1-phenyl-1,2-propanedione, 2-O-benzoyl oxime, 1-aminophenyl ketones or1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl phenyl ketone,phenyl 1-hydroxyisopropyl ketone and 4-isopropylphenyl1-hydroxyisopropyl ketone.

Photoinitiators can also comprise photoinitiators operable for use witha HeCd laser radiation source, including acetophenones,2,2-dialkoxybenzophenones and 1-hydroxyphenyl ketones, such as1-hydroxycyclohexyl phenyl ketone or 2-hydroxyisopropyl phenyl ketone(=2-hydroxy-2,2-dimethylacetophenone). Additionally, in some cases,photoinitiators comprise photoinitiators operable for use with an Arlaser radiation source including benzil ketals, such as benzil dimethylketal. In some embodiments, a suitable photoinitiator comprises anα-hydroxyphenyl ketone, benzil dimethyl ketal or2,4,6-trimethylbenzoyldiphenylphosphine oxide or a mixture thereof.

Another class of photoinitiators that may be included in a buildmaterial described herein comprises ionic dye-counter ion compoundscapable of absorbing actinic radiation and generating free radicals forpolymerization initiation. Some ionic dye-counter ion compounds andtheir mode of operation are disclosed in EP-A-0 223 587 and U.S. Pat.Nos. 4,751,102; 4,772,530; and 4,772,541.

A photoinitiator can be present in a build material described herein inany amount not inconsistent with the objectives of the presentdisclosure. In some embodiments, a photoinitiator is present in a buildmaterial in an amount of up to about 5 wt. %, based on the total weightof the build material. In some cases, a photoinitiator is present in anamount ranging from about 0.1 wt. % to about 5 wt. %.

Additionally, in some embodiments, a build material described hereinfurther comprises one or more photosensitizers. In general, such asensitizer can be added to a build material to increase theeffectiveness of one or more photoinitiators that may also be present.In some cases, a sensitizer comprises isopropylthioxanthone (ITX) or2-chlorothioxanthone (CTX).

A sensitizer can be present in a build material in any amount notinconsistent with the objectives of the present disclosure. In someembodiments, a sensitizer is present in an amount ranging from about 0.1wt. % to about 2 wt. % or from about 0.5 wt. % to about 1 wt. %, basedon the total weight of the build material.

Turning to another component of the build material described herein,build materials described herein can also comprise at least onecolorant, which can particularly be a non-luminescent colorant. Thecolorant of a build material described herein can be a particulatecolorant, such as a particulate pigment, or a molecular colorant. Anysuch particulate or molecular colorant not inconsistent with theobjectives of the present disclosure may be used. In some cases, forinstance, the colorant of a build material comprises an inorganicpigment, such as TiO₂ and/or ZnO. In some embodiments, the colorant of abuild material comprises a colorant for use in a RGB, sRGB, CMY, CMYK,L*a*b*, or Pantone® colorization scheme. In some instances, one or morecolorants of a build material described herein exhibits a white color.In other cases, a colorant exhibits a black color. Moreover, in somecases, a particulate colorant described herein has an average particlesize of less than about 5 μm, or less than about 1 μm. In someinstances, a particulate colorant described herein has an averageparticle size of less than about 500 nm, such as an average particlesize of less than about 400 nm, less than about 300 nm, less than about250 nm, less than about 200 nm, or less than about 150 nm. In someinstances, a particulate colorant has an average particle size of about50-5000 nm, about 50-1000 nm, or about 50-500 nm.

A colorant can be present in a build material described herein in anyamount not inconsistent with the objectives of the present disclosure.In some cases, colorant is present in the build material in an amount upto about 2 wt. %, or an amount of about 0.005-2 wt. %, 0.01-2 wt. %,0.01-1.5 wt. %, 0.01-1 wt. %, 0.01-0.5 wt. %, 0.1-2 wt. %, 0.1-1 wt. %,0.1-0.5 wt. %, or 0.5-1.5 wt. %, based on the total weight of the buildmaterial.

Moreover, build materials described herein, in some embodiments, furthercomprise one or more other additives. In some cases, for example, abuild material described herein further comprises one or morepolymerization inhibitors and/or stabilizing agents. A polymerizationinhibitor can be added to a build material to provide additional thermalstability to the composition. Any polymerization inhibitor notinconsistent with the objectives of the present disclosure may be used.Moreover, a polymerization inhibitor can retard or decrease the rate ofpolymerization, and/or prevent polymerization from occurring for someperiod of time or “induction time” until the polymerization inhibitor isconsumed. Further, in some cases, a polymerization inhibitor describedherein is an “addition type” inhibitor. An inhibitor described hereincan also be a “chain transfer type” inhibitor. In some instances, asuitable polymerization inhibitor comprises methoxyhydroquinone (MEHQ).

A stabilizing agent, in some embodiments, comprises one or moreanti-oxidants. A stabilizing agent can comprise any anti-oxidant notinconsistent with the objectives of the present disclosure. In somecases, suitable anti-oxidants include various aryl compounds, includingbutylated hydroxytoluene (BHT), which can also be used as apolymerization inhibitor in some embodiments described herein. Moregenerally, a single species may serve as both a stabilizing agent and apolymerization inhibitor. It is also possible, in some cases, to use aplurality of inhibitors and/or stabilizing agents, wherein differinginhibitors and/or stabilizers provide differing effects and/or worksynergistically.

A polymerization inhibitor and/or a stabilizing agent can be present ina build material in any amount not inconsistent with the objectives ofthe present disclosure. In some embodiments, a polymerization inhibitoris present in an amount ranging from about 0.01 wt. % to about 2 wt. %or from about 0.05 wt. % to about 1 wt. %. Similarly, in some cases, astabilizing agent is present in a build material in an amount rangingfrom about 0.1 wt. % to about 5 wt. %, from about 0.5 wt. % to about 4wt. %, or from about 1 wt. % to about 3 wt. %, based on the total weightof the build material.

In some embodiments, a build material described herein may containviscosity modifying agents. Non-limiting examples of viscosity modifyingagents include a saturated fatty acid or a combination of saturatedfatty acids, or an oil, such as a plant oil. The build materialsdescribed herein may comprise up to 5 wt. % up to 3 wt. %, up to 1 wt.%, up to 0.5 wt. %, or up to 0.1 wt. % of a viscosity modifying agentnot inconsistent with the object of this invention.

Build materials described herein, in some embodiments, also comprise afurther additive, such as one or more polymer additives. A polymeradditive can be especially preferred, in some instances, when a phasechange wax component is also present in the build material. Any polymernot inconsistent with the objectives of the present disclosure may beused as such an additive. For example, in some cases, such a polymeradditive is a hydrophobic polymer, including a hydrophobic polymer thatis miscible (at least 80% miscible) with one or more phase change waxcomponents described above. In some embodiments, a polymer additivedescribed herein improves the mechanical strength of a build materialdescribed herein in an uncured state. One non-limiting example of apolymer additive that may be used in some build materials describedherein is Vybar 103 (available from Baker Hughes).

In some cases, a build material described herein can include anon-curable polymer or oligomer as a polymer additive. Such a“non-curable” polymer or oligomer can exclude or be free from apolymerizable moiety described hereinabove, such as an ethyleneicallyunsaturated moiety or other photocurable moiety. Of course, it is to beunderstood that such a “non-curable” polymer or oligomer does notinclude a polymerizable moiety in the polymer or oligomer backbone(and/or in a pendant group of the polymer or oligomer) after formationof the non-curable polymer or oligomer (as opposed to not including apolymerizable moiety prior to formation of the non-curable polymer oroligomer). Non-limiting examples of non-curable polymers or oligomersdescribed herein include polyolefins such as polyethylene orpolypropylene, polydienes, polyamides, polyesters, andpolyacrylonitriles. Additionally, in some instances, a non-curablepolymer or oligomer comprises a copolymer, such as a polyolefincopolymer (e.g., a polypropylene copolymer, or PPC) or apolydiene-polyacrylonitrile copolymer (e.g., a butadiene-acrylonitrilecopolymer).

A polymer additive component of a build material described herein can bepresent in the build material in any amount not inconsistent with theobjectives of the present disclosure. In some cases, for instance, thepolymer additive component is present in an amount of up to 30 wt. %, upto 25 wt. %, up to 20 wt. %, up to 15 wt. %, up to 10 wt. %, or up to 5wt. %. In some instances, the polymer additive component is present inan amount of 1-30 wt. %, 1-25 wt. %, 1-20 wt. %, 1-15 wt. %, 1-10 wt. %,2-20 wt. %, 2-15 wt. %, 2-12 wt. %, 2-10 wt. %, 5-30 wt. %, 5-25 wt. %,5-20 wt. %, 5-15 wt. %, 5-10 wt. %, 10-30 wt. %, 10-25 wt. %, 10-20 wt.%, 15-30 wt. %, 15-25 wt. %, 15-20 wt. %, or 20-30 wt. %, based on thetotal weight of the build material.

A build material described herein also comprises a phosphor component.Any phosphor component not inconsistent with the objectives of thepresent disclosure may be used in a composition described herein. Forexample, in some cases, a phosphor component described herein comprisesan organic phosphor or luminescent species. A phosphor componentdescribed herein can also comprise an inorganic phosphor or luminescentspecies, instead of, or in addition to, an organic phosphor orluminescent species.

Moreover, a phosphor component described herein, in some embodiments, isfluorescent. As understood by one of ordinary skill in the art, such a“fluorescent” phosphor can exhibit luminescence by emitting a photonfrom a singlet excited state, as opposed to emitting a photon from atriplet excited state or other high spin multiplicity state.Additionally, a “fluorescent” phosphor can exhibit relatively rapidemission following excitation (or absorption) due to emission through aquantum mechanically “allowed” energy transition. For example, in somecases, absorption and subsequent fluorescent emission can occur in about10 nanoseconds or less. Alternatively, in other instances, a phosphorcomponent described herein is phosphorescent. As understood by one ofordinary skill in the art, such a “phosphorescent” phosphor can exhibitluminescence by emitting a photon from (or through) a triplet excitedstate or other higher spin multiplicity state, as opposed to emitting aphoton from a singlet excited state. As understood by one of ordinaryskill in the art, such phosphorescent emission can be due to intersystemcrossing of a charge carrier (e.g., an electron). Further, a“phosphorescent” phosphor can exhibit relatively slow emission followingexcitation (or absorption), due to emission through a quantummechanically “forbidden” energy transition. For instance, in some cases,absorption and phosphorescent emission occur on a timescale no shorterthan 1-10 milliseconds.

In addition, it is to be understood that a phosphor or luminescentspecies described above can be photoluminescent, as opposed to beingelectroluminescent or chemiluminescent. Such a “photoluminescent”species is understood to emit light as a result of absorption of light,as opposed to emitting light as a result of application of an electriccurrent or electric field (as in electroluminescence) or as a result ofundergoing a chemical reaction (as in chemiluminescence).

Turning again to particular chemical species or materials that can formor be included in a phosphor component described herein, a phosphorcomponent described herein can comprise, include, or be an organicphosphor. Non-limiting examples of organic phosphors include organiclaser dyes and fluorescent proteins. In some cases, a phosphor componentdescribed herein comprises one or more of fluorescein; a benzothiazole,a cyanine dye such as indocyanine green (ICG); a Dylight-700 such asDylite-700-2B; 3,3′-Diethylthiatricarbocyanine iodide (DTTCI); a cypate;a rhodamine dye such as rhodamine 6G or rhodamine B; a coumarin; aluciferin; and a green fluorescent protein (GFP) or red fluorescentprotein (RFP). Other organic phosphors may also be used.

In addition, in some cases, a phosphor component described hereincomprises, includes, or is an inorganic phosphor. In some embodiments,an inorganic luminescent species that can be used as a phosphorcomponent described herein includes a semiconductor nanocrystal orquantum dot, including a II-VI semiconductor nanocrystal such as ZnS orCdSe or a III-V semiconductor nanocrystal such as InP or InAs. In otherinstances, an inorganic phosphor comprises a Lanthanide species orLanthanide complex or compound. Other inorganic phosphors may also beused.

A phosphor component described herein can have any luminescence emissionprofile not inconsistent with the objectives of the present disclosure.For example, in some embodiments, a phosphor exhibits an emissionprofile including visible light or centered in the visible region of theelectromagnetic spectrum, such as between 430 nm and 750 nm or between450 nm and 750 nm. Thus, in some instances, the phosphor component of acomposition described herein has a peak photoluminescence emissionwavelength of 430-750 nm, 450-750 nm, or 500-700 nm. In some cases, aphosphor exhibits an emission profile including infrared (IR) light orcentered in the IR region of the electromagnetic spectrum. For example,in some instances, a phosphor described herein exhibits an emissionprofile centered in the near-IR (NIR, 750 nm-1.4 μm), short-wavelengthIR (SWIR, 1.4-3 μm), mid-wavelength IR (MWIR, 3-8 μm), orlong-wavelength IR (LWIR, 8-15 μm). Moreover, in some embodiments, aphosphor component of a composition described herein comprises aplurality of differing phosphor species having differing emissionprofiles. For example, in some cases, a first luminescent species of thephosphor component can emit in the NIR and a second luminescent speciesof the phosphor component can emit in the visible region of theelectromagnetic spectrum.

Additionally, a phosphor component of a composition described herein canhave a luminescence (e.g., photoluminescence) quantum yield (QY) andabsorption cross-section that permit detection of luminescence from thephosphor component in the composition, including when the phosphorcomponent is present in an amount described herein, and including whenthe composition is observed with the unaided or “naked” human eye of anaverage or typical human. In some embodiments, the phosphor componenthas a photoluminescence (PL) quantum yield of 0.10-1. In some instances,the phosphor component has a PL QY of 0.10-0.9; 0.10-0.8; 0.1-0.7;0.2-1; 0.2-0.9; 0.2-0.8; 0.3-1; 0.3-0.9; 0.3-0.8; 0.4-1; 0.4-0.9; or0.5-1. As understood by one of ordinary skill in the art, the PL quantumyield of a luminescent species is a ratio of the number of photonsemitted by the species to the number of photons absorbed by the species,such that a QY of 1 (or 100%) corresponds to photoluminescence in whichthe luminescent species emits one photon for each photon absorbed.Moreover, quantum yield can be measured experimentally in any manner notinconsistent with the objectives of the present disclosure. Forinstance, quantum yield of a luminescent species can be measured bycomparison of the emission of the luminescent species to the emission ofa reference species (such as a reference dye) having the same opticaldensity or absorbance at the excitation wavelength used in themeasurement.

A phosphor component of a build material described herein can be presentin the build material in any amount not inconsistent with the objectivesof the present disclosure. In some cases, for instance, the phosphorcomponent is present in an amount of up to 5 wt. %, up to 3 wt. %, up to1 wt. %, or up to 0.5 wt. %, based on the total weight of the buildmaterial. In some instances, the phosphor component is present in anamount of 0.001-5 wt. %, 0.001-3 wt. %, 0.001-1 wt. %, 0.001-0.5 wt. %,0.001-0.1 wt. %, 0.001-0.01 wt. %, 0.01-5 wt. %, 0.01-3 wt. %, 0.01-1wt. %, 0.01-0.5 wt. %, 0.01-0.1 wt. %, 0.05-5 wt. %, 0.05-3 wt. %,0.05-1 wt. %, 0.05-0.5 wt. %, 0.1-5 wt. %, 0.1-3 wt. %, 0.1-1 wt. %,0.5-5 wt. %, 0.5-3 wt. %, or 0.5-1 wt. %, based on the total weight ofthe build material.

Build materials described herein can also exhibit a variety of desirableproperties. For example, a build material described herein can have anyfreezing point, melting point, and/or other phase transition temperaturenot inconsistent with the objectives of the present disclosure. In someembodiments, a build material has a freezing or melting point consistentwith temperatures used in some 3D printing systems, including 3Dprinting systems designed for use with phase changing build materials.In some embodiments, the freezing point of a build material is greaterthan about 40° C. In some cases, for example, a build material has afreezing point centered at a temperature ranging from about 45° C. toabout 55° C. or from about 50° C. to about 80° C. In other instances, abuild material has a freezing point below about 40° C. or below about30° C.

Further, in some embodiments described herein, a build material exhibitsa sharp freezing point or other phase transition. In some cases, a buildmaterial freezes over a narrow range of temperatures, such as atemperature range of about 1° C. to about 10° C., about 1° C. to about8° C., or about 1° C. to about 5° C. In some embodiments, a buildmaterial having a sharp freezing point freezes over a temperature rangeof X±2.5° C., where X is the temperature at which the freezing point iscentered (e.g., X=65° C.).

In addition, a build material described herein, in some embodiments, isfluid at jetting temperatures encountered in 3D printing systems.Moreover, in some cases, a build material solidifies once deposited on asurface during the fabrication of a three-dimensionally printed articleor object. Alternatively, in other embodiments, a build material remainssubstantially fluid upon deposition on a surface. Solidification of abuild material, in some cases, occurs through a phase change of thebuild material, such as freezing. The phase change, in some embodiments,comprises a liquid to solid phase change or a liquid to semi-solid phasechange. In some embodiments, solidification of a build materialcomprises an increase in viscosity, such as an increase in viscosityfrom a low viscosity state to a high viscosity state, as describedfurther hereinbelow.

Further, a build material described herein can have a viscosity profileconsistent with the requirements and parameters of one or more 3Dprinting systems. In some embodiments, for instance, a build materialdescribed herein has a viscosity ranging from about 8.0 cP to about 19.0cP, from about 8.0 to about 13.5 cP, or from about 11.0 cP to about 14.0cP at a temperature of about 65° C. when measured according to ASTMstandard D2983. In other instances, a build material described hereinhas a viscosity ranging from about 8.0 cP to about 14.0 cP, from about9.5 cP to about 12.5 cP, or from about 10.5 cP to about 12.5 cP at atemperature of about 80° C. In some cases, a build material has aviscosity ranging from about 8.0 cP to about 10.0 cP at a temperature ofabout 85-87° C.

Further, build materials described herein, in some embodiments, exhibita combination of one or more desirable features. In some cases, forinstance, a build material in the non-cured state has one or more of thefollowing properties:

-   -   1. Freezing point between about 30° C. and about 65° C.;    -   2. Jetting viscosity of about 8 cP to about 16 cP at 70-95° C.;        and    -   3. Thermal stability for at least 3 days at the jetting        temperature.

Viscosity can be measured according to ASTM D2983 (e.g., using aBrookfield Model DV-II+ Viscometer). In addition, for reference purposesherein, a thermally stable material exhibits no greater than about a 35percent change in viscosity over a specified time period (e.g., 3 days)when measured at the specified temperature (e.g., a jetting temperatureof 85° C.) at the beginning and at the end of the time period. In someembodiments, the viscosity change is no greater than about 30 percent orno greater than about 20 percent, or between about 10 percent and about20 percent or between about 25 percent and about 30 percent. Moreover,in some embodiments, the change in viscosity is an increase inviscosity.

Moreover, a build material described herein in a cured state, in someembodiments, can exhibit one or more desired properties. A buildmaterial in a cured state, in some cases, comprises a build materialthat includes a curable material or polymerizable component that hasbeen at least partially polymerized and/or cross-linked. For instance,in some embodiments, a cured build material is at least about 10%polymerized or cross-linked or at least about 30% polymerized orcross-linked. In some cases, a cured build material is at least about50%, at least about 70%, at least about 80%, or at least about 90%polymerized or cross-linked. In some embodiments, a cured build materialis between about 10% and about 99% polymerized or cross-linked. In somecases, when in the cured state, a build material described herein canhave one or more of the following properties:

1. Tensile Strength of at least 2,000 psi;

2. Tensile Modulus of at least 100,000 psi;

3. Tensile elongation of at least 9%;

4. Hardness of at least 60 shore D;

5. Impact Strength of at least 0.2 ft-lb/in (Izod notched);

6. Flexural Strength of at least 1,500 psi; and

7. Flexural Modulus of at least 2,500 psi.

Build materials described herein can be produced in any manner notinconsistent with the objectives of the present disclosure. In someembodiments, for instance, a method for the preparation of a buildmaterial described herein comprises the steps of mixing the componentsof the build material, melting the mixture, and filtering the moltenmixture. Melting the mixture, in some cases, is carried out at atemperature of about 75° C. or in a range from about 75° C. to about 85°C. In some embodiments, a build material described herein is produced byplacing all components of the build material in a reaction vessel andheating the resulting mixture to a temperature ranging from about 75° C.to about 85° C. with stirring. The heating and stirring are continueduntil the mixture attains a substantially homogenized molten state. Ingeneral, the molten mixture can be filtered while in a flowable state toremove any large undesirable particles that may interfere with jettingor extrusion or other printing process. The filtered mixture can then becooled to ambient temperatures and stored until ready for use in a 3Dprinting system.

II. Support Materials

In another aspect, support materials for use with a 3D printing systemare described herein. In general, a support material described hereincomprises one or more components that provide mechanical structure toremovable supporting portions of a printed 3D article formed from thesupport material, as well as a phosphor component. As understood by oneof ordinary skill in the art, components that provide mechanicalstructure can include a variety of materials or chemical species. Forinstance, in some cases, such components are “phase change” componentsthat undergo a rapid phase change (e.g., fluid to solid) upon depositiononto a substrate. In other instances, structural components of a supportmaterial are curable. Curable components, as understood by one ofordinary skill in the art, can be deposited in a shape-unstable orquasi-unstable state and then cured (e.g., polymerized) to form ashape-stable voxel of material. Such “structural” components of asupport material can comprise or form the majority of the supportmaterial described herein. Moreover, such “structural” componentsgenerally exclude additives such as colorants, stabilizers, andinhibitors.

In general, the types of structural components of a support materialdescribed herein are not particularly limited. However, some preferredcompositions are particularly described further hereinbelow.

For instance, in some preferred embodiments, a support materialdescribed herein comprises 50-80 wt. % phase change wax component, 5-50wt. % tackifier component, and 0.001-5 wt. % phosphor component, basedon the total weight of the support material. In some such cases, thephase change wax component comprises a hydrocarbon wax, a fatty alcoholwax, a fatty acid wax, a fatty acid ester wax, an aldehyde wax, an amidewax, a ketone wax, or a mixture or combination thereof. Moreover, insome instances, the phase change wax component is present in the supportmaterial in an amount of 60-75 wt. %, based on the total weight of thesupport material. Moreover, in some embodiments, the tackifier componentof a support material described herein comprises a rosin ester, a rosinalcohol, or a mixture or combination thereof. Such a tackifiercomponent, in some cases, is present in the support material in anamount of 25-45 wt. %, based on the total weight of the supportmaterial. It is also possible for the tackifier component to bepartially replaced by a poly(alkylene oxide) component. Such apoly(alkylene oxide) component, when used, can be present in a supportmaterial in an amount of up to 30 wt. % or up to 40 wt. %. In someinstances, a poly(alkylene oxide) component is present in an amount of5-40 wt. %, 5-30 wt. %, 10-40 wt. %, 10-30 wt. %, 15-40 wt. %, 15-30 wt.%, or 20-30 wt. %, based on the total weight of the support material.Further, in some embodiments described herein, the phosphor component ofa support material has a peak photoluminescence emission wavelength of430-750 nm and/or a photoluminescence quantum yield of 0.10-1. In someinstances, the phosphor component has a peak photoluminescence emissionwavelength of 500-700 nm and a photoluminescence quantum yield of0.30-1. Additionally, in some cases, the phosphor component is presentin the support material in an amount of 0.001-0.5 wt. % or 0.01-0.5 wt.%, based on the total weight of the support material.

Alternatively, in other preferred embodiments, a support materialdescribed herein comprises 60-90 wt. % poly(alkylene oxide) component,10-30 wt. % curable morpholine component, and 0.001-5 wt. % phosphorcomponent, based on the total weight of the support material. In somesuch instances, the poly(alkylene oxide) component comprises apoly(ethylene oxide), poly(propylene oxide), or a combination thereof.Moreover, in some embodiments, the poly(alkylene oxide) componentcomprises a plurality of differing poly(aklylene oxide) species havingdiffering average molecular weights, the differing average molecularweights differing by at least a factor of 2. Further, in some cases, thepoly(alkylene oxide) component is present in the support material in anamount of 75-85 wt. %, based on the total weight of the supportmaterial. In addition, in some embodiments, the curable morpholinecomponent of a support material described herein comprises one or morespecies having the structure of Formula (I):

wherein R₁ is H or CH₃; and R₂, R₃, R₄, and R₅ are each independently H,OH, or a C1-C10 hydrocarbyl moiety. Such a curable morpholine component,in some cases, is present in the support material in an amount of 15-25wt. %, based on the total weight of the support material. Moreover, insome embodiments, the phosphor component has a peak photoluminescenceemission wavelength of 430-750 nm and/or a photoluminescence quantumyield of 0.10-1. In some instances, the phosphor component has a peakphotoluminescence emission wavelength of 500-700 nm and aphotoluminescence quantum yield of 0.30-1. Further, in some embodiments,the phosphor component is present in the support material in an amountof 0.001-0.5 wt. % or 0.01-0.5 wt. %, based on the total weight of thesupport material.

A support material described herein can also include one or more othercomponents, in addition to those described above. For example, in somecases, a support material described herein comprises at least onecolorant, at least one inhibitor, at least one stabilizing agent, or acombination of two or more of the foregoing classes of additionalcomponents.

Turning now to specific components of support materials, a supportmaterial described herein, in some embodiments, comprises a phase changewax component. A phase change wax component, in some embodiments, isoperable to assist or accelerate the solidification of the supportmaterial when the support material is cooled to or below the freezingpoint of the material. In some cases, a phase change wax component has asharp freezing point or a freezing point over a narrow range oftemperatures. In some embodiments, for example, a phase change waxcomponent freezes or solidifies over a temperature range of about 1° C.to about 5° C. or about 1° C. to about 3° C. In some cases, a phasechange wax component having a sharp freezing point freezes or solidifiesover a temperature range of X±0.5° C., where X is the temperature atwhich the freezing point is centered (e.g., X=45° C.).

Any phase change wax component not inconsistent with the objectives ofthe present disclosure may be used in a support material describedherein. In some embodiments, a phase change wax component of a supportmaterial described herein comprises a hydrocarbon wax, a fatty alcoholwax, a fatty acid wax, a fatty acid ester wax, an aldehyde wax, an amidewax, a ketone wax, or a mixture or combination thereof. Moreparticularly, the hydrocarbon wax, fatty alcohol wax, fatty acid wax,fatty acid ester wax, aldehyde wax, amide wax, or ketone wax can be anyhydrocarbon wax, fatty alcohol wax, fatty acid wax, fatty acid esterwax, aldehyde wax, amide wax, or ketone wax described hereinabove inSection I in the context of build materials.

Further, the phase change wax component of a support material describedherein can be present in the support material in any amount notinconsistent with the objectives of the present disclosure. In somecases, for instance, the phase change wax component is present in anamount of 50-80 wt. %, 50-70 wt. 5, 60-80 wt. %, or 60-75 wt. %, basedon the total weight of the support material.

A support material described herein, in some embodiments, furthercomprises a tackifier. The inclusion of a “tackifier,” in some cases,can increase the adhesiveness of the support material to a printingsubstrate and/or a build material, as described further hereinbelow. Anytackifier not inconsistent with the objectives of the present disclosuremay be used. In some embodiments, for instance, a tackifier comprises arosin ester, a rosin alcohol, or a mixture or combination thereof. Anyrosin ester or rosin alcohol not inconsistent with the objectives of thepresent disclosure may be used.

In some embodiments, a rosin ester comprises the reaction product of analcohol with a rosin acid. The alcohol, in some embodiments, comprisesmethanol, glycerol, diethylene glycol, triethylene glycol, and/orpentaerythritol. The rosin acid, in some cases, comprises one or more ofabietic acid, neoabietic acid, dehydroabietic acid, palustric acid,pimaric acid, isopimaric acid, levopimaric acid, and sandaracopimaricacid. Further, in some instances, a rosin ester is at least partiallyhydrogenated.

A rosin alcohol, in some embodiments, comprises the reaction product ofthe hydrogenation of one or more rosin acids, including rosin acidsdescribed hereinabove. Further, in some cases, a rosin alcohol comprisesa primary alcohol, such as hydroabietyl alcohol.

A tackifier can be present in a support material described herein in anyamount not inconsistent with the objectives of the present disclosure.In some cases, for instance, a tackifier is present in an amount of 5-50wt. %, 10-50 wt. %, 10-45 wt. %, 10-40 wt. %, 15-50 wt. %, 15-45 wt. %,15-40 wt. %, 15-35 wt. %, 20-50 wt. %, 20-45 wt. %, 20-40 wt. %, 25-50wt. %, 25-45 wt. %, 25-40 wt. %, 25-35 wt. %, 30-50 wt. %, or 30-45 wt.%, based on the total weight of the support material.

Support materials described herein, in some embodiments, also comprise apoly(alkylene oxide) component. Any poly(alkylene oxide) component notinconsistent with the objectives of the present disclosure may be used.For example, in some cases, the poly(alkylene oxide) component comprisesa poly(ethylene oxide), a poly(propylene oxide), or a combinationthereof. Other poly(alkylene oxide) species may also be used.

Moreover, in some embodiments, the poly(alkylene oxide) componentcomprises a plurality of differing poly(alkylene oxide) species havingdiffering average molecular weights, the differing average molecularweights differing by at least a factor of 2. For instance, in somecases, the average molecular weights differ by a factor of 1.5 to 5, 1.5to 4, 1.5 to 3, 1.5 to 2.5, 2 to 5, 2 to 4, or 2 to 3. It is further tobe understood that the “average molecular weight” described herein, forpolymeric species, is the weight average molecular weight, unlessexpressly stated otherwise.

The poly(alkylene oxide) component can be present in a support materialdescribed herein in any amount not inconsistent with the objectives ofthe present disclosure. In some cases, for instance, the poly(alkyleneoxide) component (in total) is present in an amount of 60-90 wt. %,60-85 wt. %, 60-80 wt. %, 65-90 wt. %, 65-85 wt. %, 70-90 wt. %, 70-85wt. %, 70-80 wt. %, 75-90 wt. %, or 75-85 wt. %, based on the totalweight of the support material.

Support materials described herein, in some embodiments, comprise acurable morpholine component. A “curable” morpholine component, asdescribed above, comprises a chemical species that includes one or morecurable or polymerizable moieties, as well as comprising a morpholinering, which is typically a substituted morpholine ring. As understood byone ordinary skill in the art, a substituted morpholine ring includes afunctional group other than hydrogen bonded to the carbon at the 2, 3,5, or 6 position of the 6-membered morpholine ring, or bonded to thenitrogen at the 4 position of the 6-membered morpholine ring (where theoxygen atom of the ether portion of the ring is assigned a position of1, and the nitrogen of the amine portion of the ring is assigned aposition of 4). Any curable morpholine component not inconsistent withthe objectives of the present disclosure may be used.

In some cases, the curable morpholine component comprises one or morespecies having the structure of Formula (I) below:

wherein R₁ is H or CH₃; and R₂, R₃, R₄, and R₅ are each independently H,OH, or a C1-C10 hydrocarbyl moiety (as understood by one of ordinaryskill in the art, a “Cn” hydrocarbyl moiety is a hydrocarbyl moiety thatincludes exactly “n” carbon atoms). In some such embodiments, R₁ is H orCH₃; and R₂, R₃, R₄, and R₅ are each H. In some cases, a species havingthe structure of Formula (I) is 4-acryloylmorpholine. In otherinstances, an acryloyl group is bonded to one or more of the carbonatoms at the 2, 3, 5, and 6 positions of the 6-membered morpholine ring,rather than being bonded to the nitrogen at the 4 position. In suchcases, the nitrogen atom of the morpholine ring can have a substituentR₆, which may be H or a C1-C10 hydrocarbyl moiety. Other curablemorpholine species may also be used.

The curable morpholine component can be present in a support materialdescribed herein in any amount not inconsistent with the objectives ofthe present disclosure. In some cases, for example, the curablemorpholine component is present in the support material in an amount of10-30 wt. %, 10-25 wt. %, 10-20 wt. %, 15-30 wt. %, or 15-25 wt. %,based on the total weight of the support material.

A support material described herein, in some embodiments, furthercomprises an inhibitor or stabilizing agent. An inhibitor or stabilizingagent, in some cases, can prevent or inhibit the polymerization,oxidation, or other reaction or degradation of one or more components ofa support material described herein. Any inhibitor or stabilizing agentnot inconsistent with the objectives of the present disclosure may beused. In some instances, an inhibitor or stabilizing agent comprises oneor more anti-oxidants. In some cases, for example, an inhibitor orstabilizing agent comprises an aryl compound such as butylatedhydroxytoluene (BHT). Other inhibitors or stabilizing agents may also beused.

An inhibitor or stabilizing agent can be present in a support materialdescribed herein in any amount not inconsistent with the objectives ofthe present disclosure. In some embodiments, an inhibitor or stabilizingagent is present in a support material in an amount up to about 10% byweight or up to about 5% by weight, based on the total weight of thesupport material. In some cases, an inhibitor or stabilizing agent ispresent in a support material in an amount ranging from about 0.1% byweight to about 10% by weight, from about 0.1% by weight to about 5% byweight, or from about 0.5% by weight to about 4% by weight, based on thetotal weight of the support material.

In some cases, a support material can also comprise a photoinitiator,including a photoinitiator described above in Section I, and includingin a weight percent described hereinabove in Section I.

Support materials described herein also comprise a phosphor component.

Any phosphor component not inconsistent with the objectives of thepresent disclosure may be used in a support material described herein.It is to be understood, for example, that the phosphor component of asupport material described herein can be or include any phosphorcomponent described hereinabove in Section I for build materials. Forinstance, in some cases, a phosphor component described herein comprisesa photoluminescent phosphor, such as an organic laser dye. Additionally,in some embodiments, the phosphor component of a support materialdescribed herein has a peak photoluminescence emission wavelength of430-750 nm or 500-700 nm. Moreover, in some instances, the phosphorcomponent of a support material described herein has a PL QY of 0.10-1;0.10-0.9; 0.10-0.8; 0.1-0.7; 0.2-1; 0.2-0.9; 0.2-0.8; 0.3-1; 0.3-0.9;0.3-0.8; 0.4-1; 0.4-0.9; or 0.5-1.

The phosphor component of a support material described herein can bepresent in the support material in any amount not inconsistent with theobjectives of the present disclosure. In some cases, for instance, thephosphor component is present in an amount of up to 5 wt. %, up to 3 wt.%, up to 1 wt. %, or up to 0.5 wt. %, based on the total weight of thesupport material. In some instances, the phosphor component is presentin an amount of 0.001-5 wt. %, 0.001-3 wt. %, 0.001-1 wt. %, 0.001-0.5wt. %, 0.001-0.1 wt. %, 0.001-0.01 wt. %, 0.01-5 wt. %, 0.01-3 wt. %,0.01-1 wt. %, 0.01-0.5 wt. %, 0.01-0.1 wt. %, 0.05-5 wt. %, 0.05-3 wt.%, 0.05-1 wt. %, 0.05-0.5 wt. %, 0.1-5 wt. %, 0.1-3 wt. %, 0.1-1 wt. %,0.5-5 wt. %, 0.5-3 wt. %, or 0.5-1 wt. %, based on the total weight ofthe support material.

In some embodiments, support materials having a composition describedherein can be water dispersible or water soluble. A “water dispersible”support material, in some cases, can be completely or substantiallycompletely dispersed in water within 18 hours or less, within 8 hours orless, within 2 hours or less, within 1 hour or less, within 30 minutesor less, within 15 minutes or less, within 5 minutes or less, within 3minutes or less, within 2 minutes or less, or within 1 minute or lesswhen immersed in water, with or without agitation of the water. Asupport material that is “substantially dispersed” in water, in someembodiments, is present in the water as solvated chemical species and/oras colloidal or suspended particles in an amount of at least about 80%by weight, at least about 90% by weight, at least about 95% by weight,or at least about 99% by weight, based on the total weight of thesupport material. Moreover, in some embodiments, the water is at atemperature of 20-30° C., such as a temperature of 25° C.

Moreover, in some embodiments, a support material described herein isself-emulsifying when contacted with water or a continuous aqueousphase. Additionally, in some cases, an aqueous dispersion of a supportmaterial described herein can be directly disposed of in a wastewatertreatment system without further chemical and/or physical processingprior to entry into the wastewater treatment system. In some instances,for example, an aqueous dispersion of a support material describedherein can be disposed of in a municipal wastewater treatment systemwithout further chemical and/or physical processing or treatment priorto entry into the municipal wastewater treatment system. Additionally,in some cases, a support material described herein is biodegradable.

Further, support materials described herein, in some embodiments, canhave a melting point or freezing point consistent with the temperatureparameters of one or more 3D printing systems. In some cases, a supportmaterial has a melting point ranging from about 45° C. to about 95° C.,from about 45° C. to about 70° C., from about 50° C. to about 65° C.,from about 55° C. to about 63° C., or from about 60° C. to about 62° C.Moreover, in some embodiments, a support material described herein has afreezing point ranging from about 45° C. to about 55° C., from about 47°C. to about 52° C., or from about 49° C. to about 51° C.

Further, in some instances, a support material described herein has aviscosity consistent with the requirements and parameters of one or more3D printing systems. In some cases, for example, a support materialdescribed herein has a viscosity ranging from about 9.0 centipoise (cP)to about 14.0 cP at a temperature of about 65° C., when measuredaccording to ASTM standard D2983 (e.g., using a Brookfield ModelDV-II+Viscometer). In some embodiments, a support material has aviscosity ranging from about 9.5 cP to about 12.0 cP or from about 10.0cP to 11.0 cP at a temperature of about 65° C. In other cases, a supportmaterial described herein has a viscosity ranging from about 10.0 cP toabout 19.0 cP, from about 11.0 cP to about 14.0 cP, from about 11.5 cPto about 13.5 cP, or from about 12.0 cP to about 13.0 cP at atemperature of about 80° C.

Support materials described herein can be made in any manner notinconsistent with the objectives of the present disclosure. In somecases, for instance, a method for the preparation of a support materialdescribed herein comprises the steps of mixing the components of thesupport material, melting the mixture, and filtering the molten mixture.Melting the mixture, in some embodiments, is carried out at atemperature of about 55° C. or in a range from about 40° C. to about110° C. In some embodiments, a support material described herein isproduced by placing all components of the support material in a reactionvessel and heating the resulting mixture to a temperature ranging fromabout 40° C. to about 110° C. with stirring. The heating and stirringare continued until the mixture attains a substantially homogenizedmolten state. In general, the molten mixture can be filtered while in aflowable state to remove any large undesirable particles that mayinterfere with jetting.

III. Compositions Comprising 3D Articles

In another aspect, compositions are described herein. In someembodiments, a composition comprises a three-dimensionally printedarticle comprising a build material and a support material, wherein thebuild material comprises a build material described hereinabove inSection I, and/or the support material comprises a support materialdescribed hereinabove in Section II. Any build material described inSection I may be used in a composition described herein. Similarly, anysupport material described in Section II may be used in a compositiondescribed herein. For example, in some cases, the build materialcomprises at least 70 wt. % phase change wax component; up to 30 wt. %additive component; and 0.01-5 wt. % phosphor component, based on thetotal weight of the build material. Additionally, in some embodimentsthe support material comprises 50-80 wt. % phase change wax component;5-50 wt. % tackifier component; and 0.01-5 wt. % phosphor component,based on the total weight of the support material. Other combinations ofbuild materials from Section I and support materials from Section II arealso possible.

Moreover, in some embodiments in which the composition comprises both abuild material described herein in Section I, and also a supportmaterial described herein in Section II, the phosphor component of thebuild material can differ (or have a different emission profile) thanthe phosphor component of the support material. For instance, in somecases, the build material comprises a first phosphor component having afirst peak emission wavelength, and the support material comprises asecond phosphor component having a second peak emission wavelength,wherein the first peak emission wavelength and the second peak emissionwavelength differ by a sufficient amount to permit spectral resolutionof the emission profiles of the build material and support material,either spectroscopically or by unaided eye. In some such embodiments,for example, the first and second peak emission wavelengths differ by atleast 50 nm or at least 100 nm. When a composition described hereincomprises only a build material described herein in Section I, or only asupport material described herein in Section II (as opposed to includingboth), it is to be understood that the composition can comprise, as anadditional or “complementary” component, any other build material orsupport material not inconsistent with the objectives of the presentdisclosure. In particular, when a composition described herein includesa build material of Section I, then a support material that may also bepresent in the composition can be any support material known to one ofordinary skill in the art for use with such a build material, withoutany particular limitation. Similarly, when a composition describedherein includes a support material of Section II, then a build materialthat may also be present in the composition can be any build materialknown to one of ordinary skill in the art for use with such a supportmaterial, without any particular limitation.

As described further herein, a composition or three-dimensionallyprinted article described herein, in some embodiments, comprises aplurality of layers of a build material (e.g., a build material ofSection I), wherein the layers of the build material are depositedaccording to data in a computer readable format. Moreover, at least oneof the deposited layers of build material is supported by a supportmaterial (which can, in some cases, be a support material of SectionII). In general, the support material is removable to completeproduction of the three-dimensionally printed article or object of thecomposition.

IV. Methods of Printing a 3D Article

In another aspect, methods of printing a 3D article or object aredescribed herein. Methods of printing a 3D article or object describedherein can include forming the 3D article from a plurality of layers ofa build material described herein in a layer-by-layer manner. Any buildmaterial described hereinabove in Section I may be used. For example, insome cases, the build material comprises at least 70 wt. % phase changewax component, optionally up to 30 wt. % additive component, and 0.001-5wt. % phosphor component, based on the total weight of the buildmaterial. Further, the layers of a build material can be depositedaccording to an image of the 3D article in a computer readable format.In some embodiments, the build material is deposited according topreselected computer aided design (CAD) parameters. Moreover, in somecases, one or more layers of a build material described herein has athickness of about 10 μm to about 100 μm, about 10 μm to about 80 μm,about 10 μm to about 50 μm, about 20 μm to about 100 μm, about 20 μm toabout 80 μm, or about 20 μm to about 40 μm. Other thicknesses are alsopossible.

Additionally, it is to be understood that methods of printing a 3Darticle described herein can include, for example, MJP or SLA 3Dprinting methods. For example, in some instances, a MJP method ofprinting a 3D article comprises selectively depositing layers of a buildmaterial described herein in a fluid state onto a substrate, such as abuild pad of a 3D printing system. In addition, in some embodiments, amethod described herein further comprises supporting at least one of thelayers of the build material with a support material. Any supportmaterial not inconsistent with the objectives of the present disclosuremay be used. In some cases, the support material comprises a supportmaterial described hereinabove in Section II.

A method described herein can also comprise curing the layers of thebuild material. For example, in some instances, a method of printing a3D article described herein further comprises subjecting the buildmaterial to electromagnetic radiation of sufficient wavelength andintensity to cure the build material, where curing can comprisepolymerizing one or more polymerizable moieties or functional groups ofone or more components of the build material. In some cases, a layer ofdeposited build material is cured prior to the deposition of another oradjacent layer of build material. Additionally, curing one or morelayers of deposited build material, in some embodiments, is carried outby exposing the one or more layers to electromagnetic radiation, such asUV light, visible light, or infrared light.

Alternatively, a layer of build material (e.g., a layer of depositedbuild material) is not cured (or not cured prior to formation of asubsequent layer of build material) but instead simply undergoes a phasetransition following formation to solidify the layer.

Further details regarding various methods, including “materialdeposition” methods (such as MJP) or “vat polymerization” methods (suchas SLA), are provided below.

A. Material Deposition Methods

In a material deposition method, one or more layers of a build materialdescribed herein are selectively deposited onto a substrate andoptionally cured. Curing of the build material may occur after selectivedeposition of one layer, each layer, several layers, or all layers ofthe build material.

In some instances, a build material described herein is selectivelydeposited in a fluid state onto a substrate, such as a build pad of a 3Dprinting system. Selective deposition may include, for example,depositing the build material according to preselected CAD parameters.For example, in some embodiments, a CAD file drawing corresponding to adesired 3D article to be printed is generated and sliced into asufficient number of horizontal slices. Then, the build material isselectively deposited, layer by layer, according to the horizontalslices of the CAD file drawing to print the desired 3D article. A“sufficient” number of horizontal slices is the number necessary forsuccessful printing of the desired 3D article, e.g., to produce itaccurately and precisely.

Further, in some embodiments, a preselected amount of build materialdescribed herein is heated to the appropriate temperature and jettedthrough a print head or a plurality of print heads of a suitable ink jetprinter to form a layer on a print pad in a print chamber. In somecases, each layer of build material is deposited according topreselected CAD parameters. A suitable print head to deposit the buildmaterial, in some embodiments, is a piezoelectric print head. Additionalsuitable print heads for the deposition of build material and supportmaterial described herein are commercially available from a variety ofink jet printing apparatus manufacturers. For example, Xerox, HewlettPackard, or Ricoh print heads may be used in some instances.

Additionally, in some embodiments, a build material described hereinremains substantially fluid upon deposition. Alternatively, in otherinstances, the build material exhibits a phase change upon depositionand/or solidifies upon deposition. Moreover, in some cases, thetemperature of the printing environment can be controlled so that thejetted droplets of build material solidify on contact with the receivingsurface. In other embodiments, the jetted droplets of build material donot solidify on contact with the receiving surface, remaining in asubstantially fluid state. Additionally, in some instances, after eachlayer is deposited, the deposited material is planarized and cured withelectromagnetic (e.g., UV, visible or infrared light) radiation prior tothe deposition of the next layer. Optionally, several layers can bedeposited before planarization and curing, or multiple layers can bedeposited and cured followed by one or more layers being deposited andthen planarized without curing. Planarization corrects the thickness ofone or more layers prior to curing the material by evening the dispensedmaterial to remove excess material and create a uniformly smooth exposedor flat up-facing surface on the support platform of the printer. Insome embodiments, planarization is accomplished with a wiper device,such as a roller, which may be counter-rotating in one or more printingdirections but not counter-rotating in one or more other printingdirections. In some cases, the wiper device comprises a roller and awiper that removes excess material from the roller. Further, in someinstances, the wiper device is heated. It should be noted that theconsistency of the jetted build material described herein prior tocuring, in some embodiments, should desirably be sufficient to retainits shape and not be subject to excessive viscous drag from theplanarizer.

Moreover, a support material, when used, can be deposited in a mannerconsistent with that described hereinabove for the build material. Thesupport material, for example, can be deposited according to thepreselected CAD parameters such that the support material is adjacent orcontinuous with one or more layers of the build material. Jetteddroplets of the support material, in some embodiments, solidify orfreeze on contact with the receiving surface. In some cases, thedeposited support material is also subjected to planarization, curing,or planarization and curing. Any support material not inconsistent withthe objectives of the present disclosure may be used.

Layered deposition of the build material and support material can berepeated until the 3D article has been formed. In some embodiments, amethod of printing a 3D article further comprises removing the supportmaterial from the build material, including in a manner describedhereinabove (e.g., using an aqueous or non-aqueous solvent).

Curing of the build material, when used, may occur after selectivedeposition of one layer of build material, of each layer of buildmaterial, of several layers of build material, or of all layers of thebuild material necessary to print the desired 3D article. In someembodiments, a partial curing of the deposited build material isperformed after selective deposition of one layer of build material,each layer of build material, several layers of build material, or alllayers of the build material necessary to print the desired 3D article.A “partially cured” build material, for reference purposes herein, isone that can undergo further curing. For example, a partially curedbuild material is up to about 30% polymerized or cross-linked or up toabout 50% polymerized or cross-linked. In some embodiments, a partiallycured build material is up to about 60%, up to about 70%, up to about80%, up to about 90%, or up to about 95% polymerized or cross-linked.

In some embodiments, partial curing of the deposited build material caninclude irradiating the build material with an electromagnetic radiationsource or photocuring the build material. Any electromagnetic radiationsource not inconsistent with the objectives of the present disclosuremay be used, e.g., an electromagnetic radiation source that emits UV,visible or infrared light. For example, in some embodiments, theelectromagnetic radiation source can be one that emits light having awavelength from about 300 nm to about 900 nm, e.g., a Xe arc lamp.

Further, in some embodiments, a post-curing is performed after partiallycuring is performed. For example, in some cases, post-curing is carriedout after selectively depositing all layers of the build materialnecessary to form a desired 3D article, after partially curing alllayers of the build material, or after both of the foregoing steps havebeen performed. Moreover, in some embodiments, post-curing comprisesphotocuring. Any electromagnetic radiation source not inconsistent withthe objectives of the present disclosure may be used for a post-curingstep described herein. For example, in some embodiments, theelectromagnetic radiation source can be a light source that has a higherenergy, a lower energy, or the same energy as the electromagneticradiation source used for partial curing. In some cases wherein theelectromagnetic radiation source used for post-curing has a higherenergy (i.e., a shorter wavelength) than that used for partial curing,an Xe arc lamp can be used for partial curing and a Hg lamp can be usedfor post-curing.

Additionally, after post-curing, in some cases, the deposited layers ofbuild material are at least about 80% polymerized or cross-linked or atleast about 85% polymerized or cross-linked. In some embodiments, thedeposited layers of build material are at least about 90%, at leastabout 95%, at least about 98%, or at least about 99% polymerized orcross-linked. In some instances, the deposited layers of build materialare bout 80-100%, about 80-99%, about 80-95%, about 85-100%, about85-99%, about 85-95%, about 90-100%, or about 90-99% polymerized orcross-linked.

B. Vat Polymerization Methods

It is also possible to form a 3D article from a build material describedherein using a vat polymerization method, such as an SLA method. Thus,in some cases, a method of printing a 3D article described hereincomprises retaining a build material described herein in a fluid statein a container and selectively applying energy to the build material inthe container to solidify at least a portion of a fluid layer of thebuild material, thereby forming a solidified layer that defines across-section of the 3D article. Additionally, a method described hereincan further comprise raising or lowering the solidified layer of buildmaterial to provide a new or second fluid layer of unsolidified buildmaterial at the surface of the fluid build material in the container,followed by again selectively applying energy to the build material inthe container to solidify at least a portion of the new or second fluidlayer of the build material to form a second solidified layer thatdefines a second cross-section of the 3D article. Further, the first andsecond cross-sections of the 3D article can be bonded or adhered to oneanother in the z-direction (or build direction corresponding to thedirection of raising or lowering recited above) by the application ofthe energy for solidifying the build material. Moreover, selectivelyapplying energy to the build material in the container can compriseapplying electromagnetic radiation having a sufficient energy to curethe build material. In some instances, the electromagnetic radiation hasan average wavelength of 300-900 nm, and in other embodiments theelectromagnetic radiation has an average wavelength that is less than300 nm. In some cases, the curing radiation is provided by a computercontrolled laser beam. In addition, in some cases, raising or lowering asolidified layer of build material is carried out using an elevatorplatform disposed in the container of fluid build material. A methoddescribed herein can also comprise planarizing a new layer of fluidbuild material provided by raising or lowering an elevator platform.Such planarization can be carried out, in some cases, by a wiper orroller.

It is further to be understood that the foregoing process can berepeated a desired number of times to provide the 3D article. Forexample, in some cases, this process can be repeated “n” number oftimes, wherein n can be up to about 100,000, up to about 50,000, up toabout 10,000, up to about 5000, up to about 1000, or up to about 500.Thus, in some embodiments, a method of printing a 3D article describedherein can comprise selectively applying energy to a build material in acontainer to solidify at least a portion of an nth fluid layer of thebuild material, thereby forming an nth solidified layer that defines annth cross-section of the 3D article, raising or lowering the nthsolidified layer of build material to provide an (n+1)th layer ofunsolidified build material at the surface of the fluid build materialin the container, selectively applying energy to the (n+1)th layer ofbuild material in the container to solidify at least a portion of the(n+1)th layer of the build material to form an (n+1)th solidified layerthat defines an (n+1)th cross-section of the 3D article, raising orlowering the (n+1)th solidified layer of build material to provide an(n+2)th layer of unsolidified build material at the surface of the fluidbuild material in the container, and continuing to repeat the foregoingsteps to form the 3D article. Further, it is to be understood that oneor more steps of a method described herein, such as a step ofselectively applying energy to a layer of build material, can be carriedout according to an image of the 3D article in a computer-readableformat. General methods of 3D printing using stereolithography arefurther described, inter alia, in U.S. Pat. Nos. 5,904,889 and6,558,606.

Performing a printing process described above can provide a printed 3Darticle from a build material described herein that has a high featureresolution. The “feature resolution” of an article, for referencepurposes herein, can be the smallest controllable physical feature sizeof the article. The feature resolution of an article can be described interms of a unit of distance such as microns (μm), or in terms of dotsper inch (dpi). As understood by one of ordinary skill in the art, ahigher feature resolution corresponds to a higher dpi value but a lowerdistance value in μm. In some cases, an article formed by depositing orsolidifying a build material described herein can have a featureresolution of about 500 μm or less, about 200 μm or less, about 100 μmor less, or about 50 μm or less, including at elevated temperatures. Insome embodiments, an article has a feature resolution between about 50μm and about 500 μm, between about 50 μm and about 200 μm, between about50 μm and about 100 μm, or between about 100 μm and about 200 μm.Correspondingly, in some instances, an article described herein has afeature resolution of at least about 100 dpi, at least about 200 dpi, atleast about 250 dpi, at least about 400 dpi, or at least about 500 dpi.In some cases, the feature resolution of an article is between about 100dpi and about 600 dpi, between about 100 dpi and about 250 dpi, orbetween about 200 dpi and about 600 dpi.

In a vat polymerization method such as described above, the buildmaterial may be partially cured as described in Section IVA above. Forexample, in some embodiments, selectively applying energy to the buildmaterial in the container to solidify at least a portion of a fluidlayer of the build material may include partially curing at least aportion of a fluid layer of the build material. In other embodiments,partial curing of at least a portion of a fluid layer of the buildmaterial may occur after a first layer of the build material is providedand solidified, before or after a second layer of the build material isprovided or solidified, or before or after one, several, or allsubsequent layers of the build material are provided or solidified.

Additionally, in some embodiments of a vat polymerization methoddescribed herein, after partial curing or after the desired 3D articleis formed, post-curing as described in Section IVA above may beperformed. The desired 3D article may be, for example, an article thatcorresponds to the design in a CAD file.

Some embodiments described herein are further illustrated in thefollowing non-limiting examples.

EXAMPLES Build Materials

Build materials according to some embodiments described herein wereprepared as follows. Specifically, to prepare various build materialcompositions, the components of Table I were mixed in a reaction vessel.The amounts in Table I refer to the wt. % of each component of theidentified composition, based on the total weight of the composition.For each build material composition, the appropriate mixture was heatedto a temperature of about 75-85° C. with stirring. The heating andstirring were continued until the mixture attained a substantiallyhomogenized molten state. The molten mixture was then filtered. Next,the filtered mixture was allowed to cool to ambient temperature. InTable I, “BM” means “Build Material,” and “--” means the relevantcomponent is absent from the composition. Table II provides someproperties of Build Materials 1-3. The viscosities at 80° C. and 96° C.were measured according to ASTM D2983.

TABLE I Build Material Compositions. BM 1 BM 2 BM 3 Phase Change Wax96.86  99.76  99.94  Non-Curable Polymer Additive 2.56 — — OligomericCurable Material — — — Monomeric Curable Material — — — Phosphor 0.050.11 0.05 Stabilizer 0.51 — — Colorant (Non-Phosphor) 0.02 0.13 0.01Photoinitiator — — —

In Table I above, for Build Material 1, the phase change wax componentwas a combination of non-polar hydrocarbon wax, paraffin wax, and basewax; the non-curable polymer additive was Vybar 103 (commerciallyavailable from Baker Hughes, Inc.); the stabilizing agent waspentaerythritoltetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)stearylalcohol; the phosphor was2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole); and the non-phosphorcolorant was Keyplast IRS Violet (commercially available from KeystoneAniline Corporation). For Build Material 2, the phase change waxcomponent was a blend of Permulgin 4023 (commercially available fromKoster Keunen, Inc.) and hydrogenated hydrocarbon wax resin; thephosphor was 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole), and thenon-phosphor colorant was Keyplast Blue (commercially available fromKeystone Aniline Corporation). For Build Material 3, the phosphor was2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole), and the non-phosphorcolorant was Keyplast Blue.

TABLE II Build Material Properties. Viscosity Viscosity Peak MeltingPeak Freezing at 80° C. at 96° C. Point by DSC Point by DSC (cPs) (cPs)(° C.) (° C.) BM 1 11.67 7.93 65.5 54.3 BM 2 13.1 8.67 72.5 61.1 BM 314.03 9.23 70.1 60.2

In addition to Build Materials 1-3 above, other build materialsaccording to the present invention are provided using the amounts inTable III below (in which each row corresponds to a particular buildmaterial composition). The amounts in Table III refer to the wt. % ofeach component of the relevant composition, based on the total weight ofthe composition, where it is understood that the total must equal 100wt. % in a given instance. Additionally, “PI” stands for“photoinitiator.”

TABLE III Build Material Components. Phase Non- Oligomeric MonomericChange Curable Curable Curable Stabilizer/ Wax Additive MaterialMaterial Phosphor Inhibitor PI 70-99 0-30 — — 0.001-0.5 0-1 — 70-98 1-30— — 0.001-0.5 0-1 — 70-95 2-30 — — 0.01-1  0-2 — 80-99 0-20 — — 0.01-3   0-1.5 — 85-99 2-10 — — 0.001-0.5 0-2 0-1 — 0-5  10-60 10-80  0.01-0.50-2 0.1-0.5 — — 10-30 10-80 0.001-1  0-2 0.1-1.5 — — 10-60 40-70 0.01-3 0-2 0-2 — — 10-30 40-70 0.001-0.5 0-2 0-2 — 0-5  10-30 40-70  0.01-0.50.01-2     0-1.5

Support Materials

Support materials according to some embodiments described herein wereprepared as follows. Specifically, to prepare various support materials,the components of Table IV were mixed in a reaction vessel. The amountsin Table IV refer to the wt. % of each component of the identifiedcomposition, based on the total weight of the composition. For eachsupport material composition, the appropriate mixture was heated to atemperature of about 75-85° C. with stirring. The heating and stirringwere continued until the mixture attained a substantially homogenizedmolten state. The molten mixture was then filtered. Next, the filteredmixture was allowed to cool to ambient temperature. In Table IV, “SM”means “Support Material”, and “--” means the relevant component isabsent from the composition. Table V provides some properties of SupportMaterials 1-5. The viscosities at 80° C. and 96° C. were measuredaccording to ASTM D2983. “DSC” in Table V is Differential Scanningcalorimetry.

TABLE IV Support Material Compositions. SM 1 SM 2 SM 3 SM 4 SM 5 SM 6Phase Change 64.27 70 63.73  86.08  64.14 — Wax Tackifier 35.68 28 9.1012.30  35.61 — Poly(alkylene — — 25.49  — — 80.38 oxide) Curable — — — —— 18.73 Morpholine Phosphor  0.05 0.05 0.04 0.04  0.25 0.03 Stabilizer —1.95 1.64 1.58 — 0.05 Photoinitiator — — — — — 0.81

In Table IV above, for Support Material 1 and Support Material 5, thephase change wax component was stearyl alcohol, the tackifier was aglycerol ester of hydrogenated wood rosin, and the phosphor was2,5-thiophenediylbis(5-tert-butyl-1, 3-benzoxazole). For SupportMaterial 2, the phase change wax component was stearyl alcohol, thetackifier was a hydrogenated rosin ester, the phosphor was2,5-thiophenediylbis(5-tert-butyl-1, 3-benzoxazole), and the stabilizingagent was BHT. For Support Material 3, the phase change wax componentwas stearyl alcohol, the tackifier was a hydrogenated rosin ester, thepoly(alkylene oxide) was a polyethylene glycol (PEG) having a numberaverage molecular weight of 2050, the phosphor was2,5-thiophenediylbis(5-tert-butyl-1, 3-benzoxazole), and the stabilizingagent was BHT. For Support Material 4, the phase change wax componentwas a combination of stearyl alcohol and ethoxylated behenyl alcohol,the tackifier was a hydrogenated rosin ester, the phosphor was abenzothiazole, and the stabilizing agent was BHT. For Support Material6, the poly(alkylene oxide) component was an approximately equal mixtureof PEG 1200 and PEG 425 (where the number refers to the number averagemolecular weight), the morpholine component was 4-acryloylmorpholine,the phosphor was 2,5-thiophenediylbis(5-tert-butyl-1, 3-benzoxazole),the stabilizing agent was N-nitrosophenylhydroxylamine (aluminium salt),and the photoinitiator was Irgacure 819.

TABLE V Support Material Properties. Viscosity Viscosity Peak MeltingPeak Freezing at 80° C. at 96° C. Point by DSC Point by DSC (cPs) (cPs)(° C.) (° C.) SM 1 12.67 7.64 59.7 46.9 SM 2 10 — 59.7 47.5 SM 3 10.08 —61.4 47.3 SM 4 9.78 — 61.1 46 SM 5 13.5 — 59.5 44.2

In addition to Support Materials 1-6 above, other support materialsaccording to the present invention are provided using the amounts inTable VI below (in which each row corresponds to a particular supportmaterial composition). The amounts in Table VI refer to the wt. % ofeach component of the relevant composition, based on the total weight ofthe composition, where it is understood that the total must equal 100wt. % in a given instance. Additionally, “PI” stands for“photoinitiator.”

TABLE VI Support Material Components. Phase Change Poly(alkyleneMorpholine Stabilizer/ Wax Tackifier oxide) Component Phosphor InhibitorPI 50-80  5-40 5-30 — 0.001-0.5 0-1 — 50-80  5-40 — —  0.01-0.5 0-1 —60-80 10-50 0-30 — 0.001-1  0.01-2   — 60-75 20-50 5-30 — 0.01-3 0.01-1.5  — 60-75 20-45 0-30  0-10  0.01-0.5 0-2 0-1 60-75 25-45 0-10 0-10 0.001-0.5 0-2 0.1-0.5 — — 60-90  10-30 0.001-1  0-2 0.1-1.5 — 0-10 75-85  10-30 0.01-3  0-2 0-2  0-20 — 75-85  15-25  0.01-0.5 0-20-2  0-10 — 60-90  15-25 0.001-0.5 0.01-2     0-1.5

FIG. 3 is an illustration of a portion of an embodiment of athree-dimensional article 7 formed by the three-dimensional printingsystem 2. The illustrated three-dimensional article 7 has a curvedtubular shape and is hollow on the inside. FIG. 3A is a cross-sectionalview taken from AA of FIG. 3. As illustrated, the three-dimensionalarticle 7 has an outer shell 32 formed from build material 9. The outershell 32 has an inside surface 34 that defines a hollow cavity 36 withinthe three-dimensional article 7. The hollow cavity 36 contains supportmaterial 11. The support material ills present immediately after aprinting process which forms the three-dimensional article 7. Thesupport material 11 may be later removed by a post-process.

Because of the location of the support material 11, it may be impossibleto directly observe completeness of the removal post-process by theunaided eye. But because the support material 11 contains a phosphorcomponent it may be observable. According to the illustrated embodiment,a light source 37 is used to apply electromagnetic radiation 38 to thethree dimensional article 7. The phosphor component responds to theincoming radiation 38 by emitting radiation 39 that is visible to anunaided eye.

FIG. 4 is a flowchart depicting an embodiment of a first method 40 formanufacturing a three-dimensional article utilizing a three-dimensionalprinting system 2. The three-dimensional article 7 can be a functionalproduct or it can be a test article such as a test coupon for evaluatinga post-process.

According to 42, ink supplies 12 supply inks to a printhead assembly 8.The inks include a build material ink 9 and a support material ink 11having a phosphor component.

According to 44, the printing system 2 prints the three-dimensionalarticle 7 in a layer-by-layer manner. At least some of the printedlayers individually include a region of the build material 9 and aregion of the support material 11.

According to 46, a post-process is performed upon the three-dimensionalarticle 7. This post-process can include removal of the support material11. In one implementation, the support material 11 is removed by heatingthe three-dimensional article 7 whereby the support material 11 meltsand drips away from the three-dimensional article 7. In anotherimplementation, the support material 11 is dissolved away with asolvent. In yet another implementation, the support material 11 isremoved by a heated solvent. A further implementation includes heatingto remove a bulk of the support material 11 followed by a solvent toremove residue.

When a solvent is used to dissolve the support material, the solvent canbe a single component or a mixture of co-solvents. The solvent caninclude one or more of water, isopropyl alcohol (IPA), and othercomponents. The solvent can include one or more of water, isopropylalcohol (IPA), polypropylene glycol, ethyl alcohol, ethyl acetate,methyl alcohol, and vegetable oil.

According to 48, electromagnetic radiation is applied to thethree-dimensional article 7. According to 50, an image of light emittedfrom the three-dimensional article 7 is captured. The image capture canbe performed using a scanner, a camera, or other optical detector thatis sensitive to the emitted light.

According to 52, the image is analyzed. Analyzing the image (i.e., imageanalysis) can include one or more of shape analysis, dimensionalanalysis, presence analysis, and orientation analysis, to name a fewexamples.

According to 54, a determination is made as to whether an aspect orparameter of the post-process is acceptable or within a specifiedtolerance based upon the image analysis. One example is a determinationof whether removal of the support material is complete. The criteria canbe an emission of captured light that is above a certain energythreshold in step 50.

FIG. 5 is a flowchart depicting a second method 60 for manufacturing athree-dimensional article 7 using a printing system 2. According to 62ink supplies 12 supply inks to a printhead assembly 8. The inks includea build material ink 9 and a support material ink 11 having a phosphorcomponent.

According to 64 the printing system 2 prints the three-dimensionalarticle 7 in a layer-by-layer manner. The resultant three-dimensionalarticle 7 includes portions containing support material 11.

According to 66, the three-dimensional article is processed to removethe support material 11. In one implementation, the support material isremoved by heating the three-dimensional article 7 whereby the supportmaterial 11 melts and drips away from the three-dimensional article 7.In another implementation, the support material 11 is dissolved awaywith a solvent. In yet another implementation, the support material 11is removed by a heated solvent. In a further implementation, the supportmaterial 11 is removed by a combination of heating and solventapplication.

According to 68, the three-dimensional article 7 is illuminated withelectromagnetic radiation. The electromagnetic radiation can include oneor more of ultraviolet light, visible blue light, white light, andambient light. According to 70, the three-dimensional article 7 isvisually inspected. Inspection can take place during and/or after theillumination. Any unremoved support material will emit visible light. Ifsupport material 11 is observed, then it is removed according to 72which can be similar to the removal 66. When no support material 11 isobserved, the manufacturing process 60 is complete according to 74.

FIG. 6 depicts a “test coupon” 80 that is printed as part of a processcalibration method for a post-process removal of support material. Theillustrated test coupon 80 includes a substrate 82 with a plurality ofopenings 84. The substrate is formed from build material 9. The openings84 vary in size from a large opening to a small opening according to adimension of the opening 84. In the illustrated embodiment, the openingsare circular and vary according to a diametrical dimension.

The openings are at least partially filled with support material 11. Thesupport material 11 includes a phosphor component. During a post-processremoval of the support material 11, the smaller diameter openings tendto be more difficult to completely clear.

In the illustrative embodiment, the test coupon 80 has cylindricalopenings having cylindrical axes that extend along a thickness of thecoupon 80. The thickness can have a fixed value or can vary across thecoupon in order to provide a varying axial length of the cylindricalopenings. The cylindrical openings can either pass completely throughthe test coupon and/or have a depth that is less than the couponthickness. The depth of the openings 84 can vary across the substrate.

In other embodiments, the openings 84 can have non-circular shapes suchas oval, triangular, square, polygonal, rounded polygonal or irregular.In some embodiments there may be a mixture of different opening shapesand depths. For non-circular openings 84 a “hydraulic diameter” (DH) canbe defined as D_(H)=4A/P in which A is the area of the opening and P isthe perimeter of the opening. For non-circular shapes, the hydraulicdiameter can be the dimension that varies from one opening 84 toanother. For circular shapes, the hydraulic diameter is the same as thediameter.

In yet other embodiments, the openings 84 can vary by shape. Forexample, a series of openings 84 can all have the same area but varyaccording to the perimeter shape. As an example, shapes can includecircles, polygons, and stars. For a given area, a star shaped opening 84will take longer to clear than a circular or regular polygon opening.

In a further embodiment, a single slot-shaped opening 84 can be used.The opening 84 varies in depth along the length of the slot. Theeffectiveness of the support removal process can be gauged according toa length or length percentage of the slot that is cleared.

In a yet further embodiment, the openings 84 are in the form of indiciasuch as text. The text can have a message such as “NOT COMPLETE.” Whenthe text is no longer emitting light (because the phosphor containingsupport material is removed in post-process) then the post-process wouldbe complete.

FIG. 7 depicts a method 90 of manufacturing and using the coupon 80. Theprinting system 2 is utilized to concurrently perform steps 92 and 94.According to 92, ink supplies 12 supply inks to a printhead assembly 8.The inks include a build material ink 9 and a support material ink 11.According to 94, the printing system 2 prints test coupon 80 in alayer-by-layer manner.

According to 96, a post-process removal of the support material 11 isperformed. According to 98, the coupon 80 is inspected to evaluate thepost-process effectiveness. The evaluation can be based upon a smallestor largest dimension opening that is cleared. In one implementation, theevaluation is based upon the smallest diameter or hydraulic diameterthat is completely cleared. In another implementation, the evaluation isbased upon the deepest opening 84 that is completely cleared.

According to an illustrative embodiment, the support material 86 is aphosphor ink. As part of 98, the coupon can be illuminated withelectromagnetic radiation and the inspection occurs either during orafter the illumination. Any remaining support material will emit lightand facilitate the inspection of step 98.

FIG. 8 depicts a portion 100 of a three-dimensional article 7 havingindicia 102 that become visible with a suitable illumination of thearticle 7. In the illustrated embodiment, the indicia 102 are aplurality of barcode stripes 104 having a varying spacing and width. Invarious embodiments, the indicia 102 can be machine readable, humanreadable, or both machine and human readable. The indicia 102 can be alinear set of barcodes as illustrated or a two dimensional barcode or aQR (quick response) code to name a few examples. In some embodiments,the code can be formed with varying colors.

FIG. 8A is a cross-section taken from section AA of FIG. 8. An outerportion 106 of build material 9 defines a plurality of enclosed internalchannels 108. The channels 108 are generally filled with supportmaterial 11. The channels 108 are generally enclosed therebyencapsulating the support material 11. The support material 11 buildcontains a phosphor component. When the outer portion 106 is illuminatedwith a suitable electromagnetic radiation, the support material 11 lightand the indicia 102 become visible along an outer surface 110 of theouter portion 106.

The build material 9 defines an upper cover layer 112 that helps toencapsulate the support material 11 to prevent its removal duringpost-processing. There are other unencapsulated portions of supportmaterial 11 (e.g., see FIGS. 1 and 3A) that support portions of buildmaterial 9 during a three-dimensional printing process. The upper coverlayer prevents the removal of the encapsulated support material 11during a post-process that does remove the unencapsulated supportmaterial 11. When a light source 37 is used to illuminate the indicia102 the phosphor component of the encapsulated support material emitslight through the cover layer 112 that is visible to a human and/or alight capture device such as a camera or scanner.

FIG. 9 is a flowchart that depicts a method 120 for manufacturing athree-dimensional article 7 having indicia 102. The first two operations122 and 124 are performed concurrently by a three dimensional printingsystem 2. According to 122, ink supplies 12 supply inks to a printheadassembly 8. The inks include a build material ink 9 and a supportmaterial ink 11 having a phosphor component.

According to 124, the three-dimensional printing system 2 prints thethree-dimensional article 7 in a layer-by-layer manner. Thethree-dimensional article 7 includes the outer portion 106 having theencapsulated indicia 102 as discussed with respect to FIGS. 8 and 8A.The three-dimensional article 7 can also have unencapsulated supportmaterial 11 to support otherwise unsupported portions 13 of thethree-dimensional article as described with respect to FIG. 1.

According to 126, the three-dimensional article 7 is processed to removethe unencapsulated support material 11 but to leave behind theencapsulated support material 11.

At some later time, the indicia 102 are irradiated with electromagneticradiation according to 128. The indicia 102 are read by human or machineaccording to 129. Steps 128 and 129 can occur sequentially orsimultaneously.

FIG. 10 is a flowchart that depicts a method 130 of operating andmaintaining a three-dimensional printing system 2 and manufacturing aplurality of three-dimensional articles 7. According to 132, inksupplies 12 supply inks to a printhead assembly 8. The inks include abuild material ink and a support material ink having a phosphorcomponent during operation. In some embodiments, both the build materialand the support material inks individually contain phosphor components.According to 134 a plurality of three-dimensional articles 7 aremanufactured by printing system 2.

The inks being used are phase change inks that are heated duringoperation the printing 134. The inks create a vapor environment thatdeposits the inks upon inside surfaces of the printing system 2.

According to 136 and 138 the inside surfaces of the printing system 2are illuminated with electromagnetic radiation. Also according to 136,the inks coating the inside surface are easily identified by theirradiative emissions. According to 138, the inks are cleaned from theinsides surfaces. This cleaning is facilitated by the radiativeemission.

Methods associated with FIGS. 4, 5, 7, 9, and 10 can includeilluminating support material 11 with electromagnetic radiation andobserving or capturing electromagnetic radiation that is radiated fromthe support material. In some embodiments, the illumination andobserving or capturing happens simultaneously or concurrently. In otherembodiments, the observing or capturing occurs after the illumination.

According to one embodiment, the illumination of the support materialIlls performed with ultraviolet (UV) light that can have wavelengths orspectral peaks in a range of 100 to 400 nanometers (nm). The supportmaterial responds by radiating light with a wavelength or spectral peakin a visible range of about 450 nanometers to 750 nanometers. Theillumination wavelength or spectral peak is less than the radiatedwavelength or spectral peak. The UV illumination and the observing orcapturing takes place concurrently.

According to another embodiment, the illumination of the supportmaterial 11 is performed with blue or violet light that can havewavelengths in the 380 nanometer to 495 nanometer range. The supportmaterial responds by radiating light having a wavelength that is greaterthan the illumination wavelength. The illumination and the observing orcapturing takes place concurrently.

According to yet another embodiment, the illumination of the supportmaterial 11 is performed with white light or a mixture of wavelengths.The support material responds by radiating light having a shifted ordifferent spectral distribution than the illumination. The observing orcapturing takes place after the illumination.

Materials and methods associated with FIGS. 4, 5, 7, 9, and 10 can alsovary based upon the composition of the build material ink 9 and supportmaterial ink 11 used. In one embodiment, the build material ink 9 andthe support material ink 11 are both based primarily upon phase changewax. For such a material combination, the post-process for removing theunencapsulated support material 11 can based upon exposure to a solvent.The solvent preferentially removes the support material 11 rather thanthe build material 9.

In an alternative embodiment, the build material ink 9 is at least inpart based upon an ultraviolet curable ink and has a high heatdeflection temperature. By comparison, the support material 11 is basedon a phase change wax. For such a material combination the post-processcan be based upon heating in an oven. During the post process, thesupport material 11 melts and drips off of the build material 9. Forsome implementations, the support material can be melted and removedwith hot water, a steam bath, heated mineral oil, or a specializedcleaning agent.

All patent documents referred to herein are incorporated by reference intheir entireties. Various embodiments of the invention have beendescribed in fulfillment of the various objectives of the invention. Itshould be recognized that these embodiments are merely illustrative ofthe principles of the present invention. Numerous modifications andadaptations thereof will be readily apparent to those skilled in the artwithout departing from the spirit and scope of the invention.

What is claimed:
 1. A method of manufacturing a three-dimensionalarticle comprising: forming the three-dimensional article in alayer-by-layer manner including: supplying inks to a printhead assemblyincluding a build material ink and a support material ink, the supportmaterial ink is a phase change ink including a phosphor component;printing a layer of the three dimensional article using the printheadassembly; and repeating supplying and printing until thethree-dimensional article is fully formed including a support structureformed by the support material ink; processing the three-dimensionalarticle to remove the support material ink; illuminating thethree-dimensional article with electromagnetic radiation; inspecting thethree-dimensional article for photoluminescence that is responsive tothe illumination; and verifying whether the support material has beensufficiently removed by the processing based upon the inspection;wherein the three-dimensional article is a manufacturing test coupon andwherein verifying includes determining whether the processing is withina specification based on the inspection; wherein the test couponincludes: a substrate formed from the build material ink having anoutside surface defining a plurality of openings that individually varyin size according to a dimension of each opening; and a plurality ofsacrificial portions that at least partially close the plurality ofopenings, the sacrificial portions are formed from the support materialink; the determination is based upon a dimensional range of the openingsthat are cleared of the sacrificial portions.
 2. The method of claim 1wherein the opening dimension is a hydraulic diameter.
 3. The method ofclaim 1 wherein the opening dimension is a depth that the openingextends into the substrate.
 4. The method of claim 1 wherein theopenings extend through the substrate.
 5. The method of claim 4 whereinthe substrate varies in thickness to provide a variable axial length ofthe openings.